The Associated Press contributed to this report.
A series of explosions rocked a Lake County propane gas plant, igniting a 200-foot high fireball, and sent the sound of "boom, after boom, after boom" through the neighborhood around it.
In all, eight people were injured, with at least four in critical condition.
Florida Gov. Rick Scott met with some of 200 first responders on Tuesday and was briefed on the investigation.
"What will the state assure people it will do, perhaps to prevent something like this in the future?" Scott was asked.
"You know what happens, when anything like this happens, is you have to stop and say, 'What can we do to make sure it doesn't happen again?'" said Scott.
John Herrell, of the Lake County Sheriff's Office, said early Tuesday that no one died despite massive blasts that ripped through the Blue Rhino propane plant property late Monday night.
Tavares Fire Chief Richard Keith said officials don't suspect sabotage caused the explosions, and sources close to the investigation told WFTV that one of the possible causes of the explosion could have been when a spark ignited after a forklift worker drove by while another worker was releasing gas from a propane tank.
"In my 36 years in the fire service, I've never seen anything like this," said Keith.
Officials initially scrambled to find more than a dozen employees after the explosions, and neighboring 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," Herrell said.
The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is at the scene investigating. The Occupational Safety and Health Administration (OSHA) has opened an investigation, officials said.
One ATF investigator said during a walkthrough early Tuesday, one of the larger outside tanks sprung a leak and had to be addressed.
More ATF agents, including their main expert who worked on the Texas plant explosion earlier this year, are headed to Lake County for investigations. Officials said they're giving the workers time to calm down and remember what happened before they start interviews.
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 Center.
Herrell said others drove themselves to area hospitals.
Doctors couldn't give specifics on the injuries of the three patients at ORMC, but the director of the burn unit told Channel 9 his staff has what is called the "golden hour" to get the patients in, resuscitated and to start certain procedures.
The victims' airways can also be burned from heat and from toxins they might have breathed in, officials said, so they often needed to be put on a ventilator.
And with third-degree burns, the skin can be destroyed not just on the surface but the layers of injury can be very deep, said Dr. Howard Smith.
"The full thickness of the skin is destroyed, usually requiring surgery and a grafting and that probably may be, that's what we worry may be required for these patients," said Smith.
Tavares Fire Department Battalion Commander Eric Wages said five workers walked up to a command center firefighters set up near the plant Monday night with skin hanging off their arms, torso and faces. He said their arms were outstretched and they were in complete shock.
Blake Cottle lives in Mount Dora, about 10 miles away from where the propane tanks blew up on 300 County Road 448.
"I have heard tons of booms for at least 30 minutes," Cottle told WFTV.
"As you listened to it more, it sounded like a lot of explosions. The sky was bright orange and it was flashing," WFTV viewer Ashley McCormick said. "There were huge fireballs shooting up into the sky. And obviously lots of smoke."
"I grabbed my jacket and cat and went to the car. [I] didn't even have time to get shoes," said resident Jerri Wohlers.
Wohlers lives directly behind the Blue Rhino plant. She said the sound of propane tanks exploding woke her from a deep sleep, Monday night.
"It sounded like cannons," Wohlers said. "It was nuts."
Burnt and bent pieces of propane tanks littered her property.
WFTV also spoke with resident Mariah Ryle, who said, "The whole house shook and it was just explosion after explosion. The fire was actually so tall that I walked out my front door and just saw, like my neighbors across the street, I saw it over their roof."
Herrell said an evacuation zone was initially a 1-mile radius, but had been reduced to a half-mile radius.
The evacuation was later lifted and residents were able to return to their homes.
The Blue Rhino plant, which is northwest of Orlando, refills propane tanks typically used gas grills and other home uses. There were some 53,000 20-pound canisters at the plant on Monday.
Smoke still billowed Tuesday morning 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 20-pound 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 said.
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 20-feet-by-20-feet about 100 yards from the plant's loading dock in an area where the 20-pound 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 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 struck 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 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 paid a $2,295 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."
Keith said the explosions shook his house several miles from the plant.
"It truly sounded like a car hit our house," he said.
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.