LAFAYETTE, LA. - Six cars of a freight train derailed Saturday, including one that began leaking hydrochloric acid, prompting thousands to evacuate homes, businesses and a nursing home within one mile of the wreck.

The spilled acid sent a toxic cloud over the area, and at least five people, including two railroad workers, were taken to a hospital and treated after they complained of skin and eye irritation, said Lafayette Parish sheriff's Lt. Craig Stansbury.

A nursing home with 161 residents was evacuated, said Dr. Jimmy Guidry, the state health officer. About 35 of the residents deemed too frail to travel were taken to area hospitals, he said.

Police walked door to door notifying residents of the mandatory evacuation in an area with an estimated population of 3,500.

"We're advising them to take enough supplies for approximately 48 hours," Stansbury said.

Mona Hebert and Jeffrey Ferrara said they were rousted from their home around 3:45 a.m. and told they had two minutes to leave. Ferrara lost his home in Hurricane Katrina and has been staying with friends like Hebert since then.

Hydrochloric acid can cause respiratory problems and skin and eye irritation, according to Joe Faust, a spokesman for the Texas-based BNSF Railway that operated the train involved in the spill.

An estimated 8,000 to 10,000 gallons of the acid was spilled, he said. The acid formed a yellowish pool at the site of the derailment.

A train car carrying ethylene oxide, used in agricultural products and as a sterilizer for medical supplies, was overturned but was not leaking, said Rodney Mallett, a spokesman with the Louisiana Department of Environmental Quality.

BNSF was using lime to neutralize the hydrochloric acid. Cleanup workers will either dig or vacuum up the acid and lift the cars back onto the track, Mallett said.

Faust did not speculate on how long the cleanup might take but said residents wouldn't be allowed back into the area until officials are certain the hazardous material is gone.

The Red Cross has set up a shelter at a high school and was gearing up to handle as many as 500 people, shelter manager Jacqui Picard said.