TAVARES, FL (CNN) — Equipment failure and human error likely caused propane tank cylinders to explode at a central Florida refilling plant late Monday, a fire official said Tuesday.
The blasts at the Blue Rhino plant in Tavares injured eight plant workers, said John Herrell of the Lake County Sheriff's Office.
Residents nearby saw a pulsating glow in the sky. One Tavares resident, Norma Haygood, told CNN affiliate WESH it felt like "bombs going off."
The fire was out by 2 a.m., three hours after the explosions began, and authorities are investigating the cause, according to Tavares Fire Chief Richard Keith.
Keith, who lives a few miles away from the fire, said he "knew it was bad right off the bat."
"It truly sounded like a car hit our house," he said.
There had been earlier reports of 15 missing workers, but all 15 were found safe, Keith said. Some had fled the scene; some drove themselves to hospitals.
No residents were hurt, authorities said.
There were 53,000 20-pound cylinders of propane at the facility -- more than a million pounds in all, Herrell said.
Firefighters immediately set up a half-mile evacuation area around the plant. The nearest homes -- about 50 of them -- are about three-quarters of a mile away, Herrell said. And they began pouring water onto the facility.
Trucks parked at the plant went up in fireballs as the cylinders they were carrying exploded. The nighttime sky flickered in hues of orange.
"You could see the explosions from across the lake," said Ashley McCormick, a resident in nearby Mount Dora. "They were very intense."
There were 24 employees at work at the time of the blasts, according to Scott Brockelmeyer, a spokesman for Ferrellgas, the parent company of Blue Rhino. He said the company is cooperating with investigators.
The incident was "as sobering as you can possibly imagine," he told CNN. "We're sending good vibes their way from all over the country."
The employees perform such tasks as refurbishing cylinders and loading them on palates and vehicles. There were some management personnel on site as well, the spokesman said.
Brockelmeyer confirmed that several employees were injured and had been taken to hospitals.
The plant produces 2.3 million tanks annually, and serves all of Florida, southern Georgia and southern Alabama, he said. It opened in 2004.
Brockelmeyer would not speculate on the cause of the explosion and declined to comment on the fire chief's statement that equipment failure and human error likely caused the incident.
"The fact that there are no fatalities is a blessing," said John Drury, the city administrator of Tavares, a community of some 14,000 people about 30 miles northwest of Orlando. "This was a big deal, and a lot of people responded quickly."
Now, the focus shifts to what caused the blasts.
The Blue Rhino facility refills propane tanks used in gas grills. The company's tank exchange service allows customers to trade in an empty tank for a full one at retail locations.
The Occupational Safety and Health Administration fined Blue Rhino in 2011 over a "serious" safety violation involving tools and equipment. It is not clear whether safety violations had anything to do with the fire.
According to Brockelmeyer, the 2011 OSHA violation was due to an air nozzle at the facility that had a missing component. He did not give CNN any further information about the component or what it does.
-- CNN's Marlena Baldacci contributed to this report.