Flames can be seen from the air after an explosion happened at the sight of a train derailment in southern Jefferson County, just south of Louisville, Ky, Wednesday, Oct. 31, 2012.

LOUISVILLE, Ky. - Flames from a derailed train car sent people rushing out of neighborhoods and an entire town near Louisville on Wednesday while firefighters tried to douse the chemical blaze that left three workers badly burned.

Some people forced from their homes faced a long night on cots in shelters set up after the blaze - sparked by a cutting torch that ignited leaking vapors - broke out shortly after 1 p.m. EDT.

Officials in West Point, a short distance from the fire, ordered its nearly 1,000 residents to get away from the flames and the potential health hazards posed by the burning chemicals.

About two dozen people took shelter Wednesday night at a nearby elementary school. Resident Lisa Johnson was wrapped in a blanket outside the school, where she was taking drags from a cigarette.

"I put the grandkids in the car, forget their jackets and my jacket," she said. "Hopefully we can go home soon. I need clothes, a coat, a shower."

Police, firefighters and emergency workers went door to door to tell stunned residents to get out of town.

Another West Point resident, Steven White, said he fed his dog and then hit the road.

"I hope we're not here too long," he said. "This is tough."

The town was part of an evacuation within a 1.2-mile radius of the fire. The order also affected nearly 140 residences in southwest Louisville.

The blaze broke out while workers were using a cutting torch or welder to separate two of the cars that derailed Monday evening, said Lt. Col. Rick Harrison, assistant chief with the suburban Buechel Fire Department.

"Sparks ignited the vapor from the chemical itself," Harrison said.

Flames and thick, black smoke spewed out between two train cars while fire hoses shot almost 2,000 gallons of water a minute at the blaze. Officials cut off access to the derailment site and the nearby communities.

The three workers suffered severe burns and were taken to University of Louisville hospital. Authorities had not released their names but said one was in very critical condition, another in critical condition and the third in serious condition. A previous briefing had the three in better condition.

"The workers that are here are highly trained and this is one of those freak accidents that occurs unfortunately," Harrison said.

The fire was contained to a tanker car that had contained flammable butadiene gas, officials said.

They said they were letting residual amounts of the chemical burn out and the fire was contained inside the insulated tanker car.

Butadiene is a colorless, flammable gas that smells mildly like gasoline, according to the National Institute for Occupational Safety and Health. It is shipped as a liquefied, compressed gas. It can cause irritation to the eyes, nose and throat and drowsiness and dizziness. Exposure also can damage the central nervous system and the reproductive system.

Another big concern was that the burning rail car was only a few feet from other derailed tankers that had carried hydrogen fluoride, authorities said.

Hydrogen fluoride is a colorless gas with a sharp, pungent, irritating odor, according to the U.S. Environmental Protection Agency. Inhalation can cause severe respiratory damage in humans. It is used in the glass etching, electronic and chemical industries.

People living beyond the evacuation area but within five miles of the blaze were being told to stay indoors, close all windows and doors, bring pets inside and turn off their heating and air conditioning systems.

Doug Hamilton, director of the Louisville Emergency Management Agency, said two other workers were injured but refused to be transported to the hospital.

Hamilton said the workers were wearing respiratory gear when the fire erupted.

They work for R. J. Corman, one of the contractors helping to clean up the derailment, according to The Courier-Journal.

Workers on Wednesday had been planning to move two rail cars containing the hydrogen fluoride that were part of a derailment Monday.

Thirteen cars of a Paducah & Louisville Railway train carrying hazardous chemicals derailed Monday morning near Dixie Highway. Nine of the 13 derailed cars contained hazardous materials.

A leak of a potentially explosive material was contained after the derailment, but crews have been working to put the railroad cars back on the track or remove them and the highway remained closed.