A series of explosions rocked a central Florida propane gas plant, igniting a 65-metre high fireball, and sent the sound of "boom after boom after boom" through the neighbourhood around it.
Eight people were injured, with at least four in critical condition.
John Herrell of the Lake County Sheriff's Office said that no one died despite massive blasts that ripped through the Blue Rhino propane plant property late Monday night (Tuesday, NZ time). Officials initially scrambled to find more than a dozen employees after the explosions.
Neighbouring houses were evacuated, but no damage to them was reported.
"Management is comfortable saying all of those they knew were there tonight have been accounted for," he said.
Tavares Fire Chief Richard Keith said possible causes of the explosion may be either equipment malfunction or human error. Sabotage was not suspected.
The US Occupational Safety and Health Administration launched an investigation, as did the Florida State Fire Marshall's office.
One person injured in the explosion was listed in critical condition at University of Florida Health Shands Hospital and three others were listed in critical condition at Orlando Regional Medical Centre. Herrell said some others drove themselves to area hospitals.
Tavares Fire Department Battalion Commander Eric Wages said five workers walked up to a command center firefighters set up near the plant with skin hanging off their arms, torso and faces. He said their arms were outstretched and they were in complete shock.
The Blue Rhino plant, which is northwest of Orlando, refilled propane tanks typically used gas grills and other home uses. There were some 53,000 9kg canisters at the plant on Monday.
Smoke is still billowing from a storage container on the property, which consists of a couple of warehouses next to each other. The parking lot was littered with thousands of blackened propane containers.
Nearby, three 33,000-pound tanks of propane sat untouched. Lake County Battalion Chief Chris Croughwell said the hoses designed to spray water on the large tanks in case of fire, did not go off as planned because they had to be manually activated. "Most sane people don't stick around for an event like this," he added.
Tavares Mayor Robert Wolfe said Tuesday that he was surprised to learn the hoses at the plant had to be manually activated. If Blue Rhino reopens the plant, Wolfe said he plans to raise the safety issue. "That way, it's fail safe," Wolfe said. "We're lucky those tanks didn't explode."
One of the large tanks had a small leak that was detected mid-morning, so fire officials poured water on it and later began draining it, Wolfe said. The threat was considered minimal and no evacuation was ordered, he said.
The Florida Division of Emergency Management responded overnight and briefed Gov. Rick Scott.
Gene Williams, a third-shift maintenance worker at the plant, said he was at the back of the warehouse when he heard two loud explosions. Most of the workers were inside the facility, but there were about five in the parking lot.
When he went to look outside, there was a fireball about 6m by 6m about 30m from the plant's loading dock in an area where the propane canisters are stored on plastic pallets.
After that, a forklift driver stumbled into the building. He had flesh hanging off his hands, and his legs and face were burned. Williams said he got the man in a van as the cylinders from the 20-pound tanks starting falling down around them.
He said they were doing repairs and painting the tanks when one of the paint lines had broken, but it was repaired. The workers were getting ready to go home when the explosion happened.
Based on what the forklift operator told him, the explosion was likely caused by a "combination of human error and bad practices, possibly. I don't want to speculate any further, that's what the forklift driver was telling me."
Williams said the forklift driver told him, "'I did what they told me to do, I did what they told me to do, and then this happened.'"
"Something in that area must have triggered it. I don't know if he did something or something else triggered it," Williams said.
Williams said they were able to cut off propane to the three big tanks. But they weren't able to get to the switch for the cooling hoses.
"It was too violent, too hot, to get in there and turn them on," he said.
Williams said one of the injured people was hit by a car trying to run across the road.
The Florida Highway Patrol confirmed that 29-year-old Leesburg resident Kaghy Sam was struck by an SUV driven by 72-year-old Gene Batson on a road near the Blue Rhino plant.
A statement from the FHP said that Sam was running on the road "due to a large fire and several explosions" just before 11 p.m. Monday and "ran into the direct path" of Batson's vehicle.
Sam was flown to Ocala Regional Medical Center with serious injuries.
No charges were filed in the accident.
Blue Rhino is a subsidiary of Kansas-based national propane provider Ferrellgas. Spokesman Scott Brockelmeyer said Tuesday he didn't have information available about the safety water hoses.
"It's as sobering a situation as you can possibly imagine," Brockelmeyer said. "We have folks who are injured, and we've got Blue Rhino and Ferrellgas employees across the country who are keeping them in their prayers and sending good vibes their way."
Brockelmeyer said there were 14 full-time employees and 10 part-time workers in the plant when the explosions occurred Monday night.
Ferrellgas did pay a US$2295 fine in November 2011 following an OSHA inspection that found a component at the end of an air hose used in the consumer tank refurbishing process was not present.
Brockelmeyer said the company corrected the issue and added that "the process is performed in area away from where the tanks are filled .... so no product was being processed in that area."
Croughwell said firefighters who responded to the initial fire had to wait to enter plant site because conditions were so dangerous. Just as they were finally about to go in, four tractor-trailers parked next to the large propane tanks caught fire.
If the large tanks exploded, Croughwell said, "it would have wiped us out."
Video footage on WESH-TV in Orlando showed fires burning through trucks used to transport propane tanks, which were parked at the plant. The fire sent plumes of smoke into the air hours after the blast.
Keith said the explosions shook his house several kilometress from the plant. "It truly sounded like a car hit our house," he said.
Herrell said about 50 homes were evacuated Monday night but residents were allowed back in about four hours later.
Marni Whitehead, 33, who lives less than a mile from the plant, said she was in bed ready to go to sleep when she heard a loud boom.
She ran outside and saw other neighbors outside and then they saw the explosions.
"We knew right away it was the plant, the propane plant," Whitehead said. "After that, it was just sort of panic."
Whitehead likened the explosions to Fourth of July fireworks. "And it was just boom after boom after boom," she said.
Herrell said officials believe the fire was contained and wouldn't spread to another part of the plant.
According to the Leesburg Daily Commercial, the plant was built in 2004 and employs fewer than 50 people.