(CNN) -- Equipment failure and human error likely caused the 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.
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 is out and authorities are investigating the cause, according to Tavares Fire Chief Richard Keith.
There had been earlier reports of 15 missing workers, but everyone known to be there has been accounted for, Keith said. Some had fled the scene; some drove themselves to hospitals.
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," Keith said.
There were 53,000 20-pound cylinders of propane at the facility -- more than a million pounds in all, said John Herrell, a spokesman for the Lake County Sheriff's Office.
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."
By 2 a.m., about three hours after the explosions began, fire crews finally gained a handle on the situation.
Fortunately, all 15 of the missing workers were found safe. .
No residents were hurt.
"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.
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