NATIONAL NEWS — A recap of the developments that began Thursday night:
The violence began late Thursday with the robbery of a 7/11 convenience store, not long after the FBI released images of two suspects in the Boston Marathon bombings, Massachusetts State Police spokesman Col. Timothy Alben said.
Soon after, in Cambridge, across the Charles River from Boston, a Massachusetts Institute of Technology police officer was fatally shot while he sat in his car, the Suffolk County District Attorney's Office said in statement. Police believe the bombing suspects were responsible for the shooting.
The same two suspects, according to authorities, then hijacked a car at gunpoint in Cambridge. They released the driver a half-hour later at a gas station. As police picked up the chase, the car's occupants threw explosives out the windows and shot at officers, according to the Suffolk County District Attorney's Office.
Officers fired back, wounding one of the men, possibly the person identified by the FBI as "Suspect No. 1." The man died at Beth Israel Hospital. He had bullet wounds and injuries from an explosion, according to officials. The second man apparently escaped on foot.
Richard H. Donohue Jr., 33, a three-year veteran of the transit system police force, was shot and wounded in the incident and taken to a hospital, a transit police spokesman said Friday. The officer's condition was not immediately known.
[Updated 8:44 a.m. ET]
Police activity in Watertown -- where authorities believe they last saw "Suspect No. 2" during a chase overnight -- seems to be picking up, CNN's Deborah Feyerick reports from the community. A helicopter is hovering over a building, and reporters are being asked to move back from where they were.
[Updated 8:30 a.m. ET]
The Federal Aviation Administration has ordered a 3.5-nautical-mile temporary flight restriction over Boston "to provide a safe environment for law enforcement activities." The restriction is from the surface to 3,000 feet, according to the FAA website.
[Updated 8:21 a.m. ET]
"All taxi service in the city of Boston has been suspended pending further notice," Boston police said on its official Twitter account.
This meshes with authorities' request that all of Boston and many of its suburbs stay indoors -- with doors locked -- until further notice. All public transportation in Boston already has been suspended, schools are closed, and Amtrak service from Boston to Providence, Rhode Island, also has been suspended.
[Updated 8:16 a.m. ET]
The Boston-area transit police officer who was shot and wounded overnight is Richard H. Donohue Jr., 33, a three-year veteran of the force, a transit police spokesman said Friday. Donohue was shot during the manhunt for the Boston Marathon bombing suspects.
[Updated 8:14 a.m. ET]
Several sources tell CNN that the dead suspect has been identified as Tamerlan Tsarnaev, 26, and the one still being sought is Dzhokhar Tsarnaev, age 19.
[Updated 8:10 a.m. ET]
The suspects involved in the Boston bombings are brothers originally from the Russian Caucasus and had moved to Kazakhstan at a young age before coming to the United States several years ago, according to a source briefed on the investigation, CNN's Deborah Feyerick reported.
The older of the two brothers had the first name Tamerlan, had studied at Bunker Hill Community College, and wanted to become an engineer, the source said. He then took a year off to train as a boxer, according to the source.
The source said that a posting on a social media site in his name included the comments: "I don't have a single American friend. I don't understand them."
The source added that it should not be assumed that either brother was radicalized because of their Chechen origins.
[Updated 8:07 a.m. ET]
"All of Boston" should shelter in place, Massachusetts Gov. Deval Patrick has just told reporters. The same applies to suburbs of Watertown, Newton, Belmont, Cambridge and Waltham, he said.
By shelter in place, Patrick said he meant people should stay indoors, keep doors locked and not answer doors for anyone except for police.
Patrick also has confirmed to reporters that one Boston bombings suspect is dead and the other is on the loose.
-- A Massachusetts Bay Transportation Authority officer was "seriously wounded" and is in surgery right now.
-- An MIT security officer was killed.
[Updated 7:59 a.m. ET]
A recap of what authorities are telling Boston-area residents to do: Police ordered businesses in the suburb of Watertown and nearby communities to stay closed and told residents to stay inside and answer the door for no one but authorities.
The subway and Amtrak train systems have been shut down. Every Boston area school is closed.
"It's jarring," said CNN Belief blog writer Danielle Tumminio, who lives in Watertown.
[Updated 7:58 a.m. ET]
The Boston bombings suspect who currently is on the run has been in the United States for "at least" a couple years, a federal law enforcement source tells CNN.
[Updated 7:40 a.m. ET]
Boston police say on Twitter: "Door-to-door search 4 suspect in Watertown continues. Uniformed officers searching. Community consent critical."
[Updated 7:39 a.m. ET]
The suspects in the Boston Marathon terror attack were brothers, a terrorism expert briefed on the investigation said, according to CNN's Deborah Feyerick.
[Updated 7:34 a.m. ET]
One of two suspects in the Boston Marathon bombing -- the man police were looking for Friday morning -- has a name that is common among people from the North Caucasus, a source with knowledge of the investigation said Friday. That region includes the breakaway Russian republic of Chechnya.
Earlier Friday, The Associated Press reported that the two suspects in the Boston Marathon bombings are brothers believed to be from Chechnya.
[Updated 7:32 a.m. ET]
Police in the Boston-area community of Cambridge say the public should "clear area of Norfolk Street in Cambridge." "Ongoing investigation. Potentially dangerous," Cambridge police said on Twitter.
[Updated 7:29 a.m. ET]
Boston police have given a heads-up to the public: They'll be conducting a "controlled explosion" -- basically neutralizing a suspicious object -- near the area of Commonwealth Avenue and Charlesgate.
[Updated 7:28 a.m. ET]
Recapping what a doctor at Boston's Beth Israel told reporters this morning about the death of the man police believe is "Suspect No. 1" in the Boston bombings: He had bullet wounds and injuries from an explosion, the doctor said.
The doctor said he didn't know the cause of death, and he didn't know what the explosion was. The suspect was pronounced dead after unsuccessful attempts to reanimate him, a hospital spokesman said.
Police said the man believed to be "Suspect No. 1" was wounded in Watertown near Boston after a pursuit. That pursuit came about after the fatal shooting of a Massachusetts Institute of Technology police officer, authorities said.
[Updated 7:03 a.m. ET]
The Associated Press has reported that the two suspects in the Boston Marathon bombings are brothers believed to be from Chechnya.
[Updated 6:48 a.m. ET]
More transportation options in an out of Boston are being shut down as police look for "suspect No. 2" in the Boston Marathon bombings. Amtrak train service between Providence, Rhode Island, and Boston has been suspended, Amtrak said Friday.
This comes after the Massachusetts Bay Transportation Authority shut down Boston-area bus, subway, commuter rail, and ferry routes.
The FBI on Thursday released an image of what it called "suspect No. 2" in Monday's Boston Marathon bombings. Authorities said Friday that they're looking for him in the Boston suburb of Watertown.
[Updated 6:23 a.m. ET]
The person who was shot and killed in the Boston Marathon terror attack manhunt is believed to have had explosives on his body, a law enforcement official with knowledge of the investigation said Friday.
[Updated 6:19 a.m. ET]
Here are more details about the public transportation shutdown in Boston: All Massachusetts Bay Transportation Authority service is suspended at the request of the police, Joe Pesaturo, the authority's public information officer, said Friday. This includes bus, subway, commuter rail, and ferry routes in the Boston area.
This comes as police say they're continuing to hunt down one of the suspects in Monday's Boston Marathon terror attack.
[Updated 5:59 a.m. ET]
"Harvard University is closed due to public safety concerns. Please continue to watch this page for updates," the university announced on its website.
[Updated 5:55 a.m. ET]
President Obama was briefed overnight on the events happening in Watertown, CNN's Brianna Keilar reports.
[Updated 5:51 a.m. ET]
"Vehicle traffic in and out of Watertown suspended," say Boston Police on official Twitter account.
[Updated 5:43 a.m. ET]
Mass transit in Boston has been suspended at the request of the police, says Joe Pesaturo, spokesman for the Massachusetts Bay Transportation Authority.
[Updated 5:37 a.m. ET]
Boston Police, via its official Twitter account, says businesses near 480 Arsenal Street in Watertown, Massachusetts, are closed until further notice. Employees are also instructed to stay home.
[Updated 5:20 a.m. ET]
MIT cancels Friday's classes, according to a letter from Israel Ruiz, the school's executive vice president and treasurer, and school Chancellor Eric Grimson.
"MIT suffered a tragedy last night: an MIT Police officer was shot and killed on our campus in the line of duty," says the letter, addressed to the MIT community. "While the circumstances around the officer's death remain the subject of an active investigation, what is certain is that the officer gave his life to defend the peace of our campus. His sacrifice will never be forgotten by the Institute. We are thinking now of his family, and our hearts are heavy. In consultation with faculty chair Sam Allen, we have decided to cancel classes today (Friday). All employees are encouraged to use their best judgment about whether they are prepared to come in to work today: any absence today will be considered excused."
[Updated 5:03 a.m. ET]
Police in Watertown sending robocalls to residents instructing them to stay indoors, reports CNN's Drew Griffin.
[Updated 4:45 a.m. ET]
One of the suspects believed to have planted bombs at the Boston Marathon is dead after a shootout with police, a police spokesman said.
[Updated 4:21 a.m. ET]
The suspect on the loose in Watertown, Massachusetts, matches the description of Suspect 2 -- a man pictured wearing a white cap - wanted in connection with the bombings at the Boston Marathon on Monday, police said early Friday.
[Updated 3:54 a.m. ET]
Massachusetts State Police, via Twitter: "Police will be going door by door, street by street, in and around Watertown. Police will be clearly identified. It is a fluid situation."
[Updated at 3:48 a.m. ET]
Massachusetts State Police, on its official Twitter feed, warns Watertown residents to stay in their homes and to not answer the door "unless it is an identified police officer." "If any concerns about someone at door, call 911 immediately. Repeat--Do not answer door, stay away from windows, keep doors locked," the state police says in another tweet.
[Updated 2:40 a.m. ET]
Massachusetts State Police spokesperson Dave Procopio said that they believe multiple possible explosive devices were used against police tonight during this incident at Watertown. It was unclear if the incident, which followed a police chase of a stolen vehicle, was related to the shooting on the MIT campus or any other incident in the Boston area.
[Updated 2:31 a.m. ET]
FBI spokesman Martin Feely tells CNN's Susan Candiotti: "We are engaged with our partners trying to determine if there is a connection." CNN's Drew Griffin, who is on the scene in Watertown, Massachusetts, said FBI agents are on the scene.
[Updated 2:21 a.m. ET]
MIT releases statement on shooting death of campus police officer: "MIT is heartbroken by the news that an MIT Police officer was shot and killed in the line of duty on Thursday night on campus, near Building 32 (the Stata Center). Our thoughts are now with the family." http://bit.ly/15lcg2r
[Updated 2:19 a.m. ET]
Boston Police Department's official Twitter feed says "there is an active incident ongoing in Watertown. Residents in that area are advised to remain in their homes. More details when available."
[Updated 2:07 a.m. ET]
CNN's Gabe Ramirez on the scene in Watertown, Massachusetts, says that authorities are ordering people in the area to shut off their cell phones.
[Updated 1:49 a.m. ET]
At least one person was arrested in Watertown, Massachusetts early Friday morning, stripped naked before being taken in custody, CNN photojournalist Gabe Ramirez observed. It is unclear if this arrest was related to the shooting at Massachusetts Institute of Technology campus or any other incident in Boston the area.
[Updated 1:23 a.m. ET]
Dozens of police have rushed to an area of Watertown, Massachusetts, just over two miles from Cambridge, said CNN's Drew Griffin, who is near the scene. A "very large event has taken place," Griffin said. There were reports that explosives were involved.
[Posted at 12:45 a.m. ET]
A university police officer has died after being shot on the Massachusetts Institute of Technology campus in Cambridge late Thursday, state police spokesman Lt. Mark Riley said. The MIT officer was responding to a disturbance when he was shot, according to the state district attorney's office. He sustained "multiple gunshot wounds."
State police and the FBI were called in after the shooting and found the campus policeman near Building 32 on MIT's campus. He was taken to Massachusetts General Hospital, where he was pronounced dead, the district attorney's office said. Dozens of officers surrounded and cordoned off the building, known as the Stata Center, which houses computer science laboratories as well as the department of linguistics and philosophy, according to MIT's website.