Townspeople and night-shift workers at a textile mill heard the scrape of metal and a house-shaking boom. Then, in rolled a greenish-yellow fog that smelled powerfully like bleach, searing their eyes and lungs and making them cough and gasp.

"I took a breath. That stuff grabbed me," said Charles Reyes Littleeagle, a volunteer firefighter who ran to the scene. "It gagged me and brought me down to my knees. I talked to God and said, 'I am not dying here."'

At least eight people died and more than 250 were sickened after a freight train carrying toxic chlorine gas (search) crashed early Thursday in one of the nation's deadliest chemical spills in years.

Authorities said all of the fatalities appeared to have been caused by the released gas. Five workers died at the mill. A man's body was found in a truck near the plant. Another man died in his home. The train engineer died at a hospital.

About 5,400 residents within a one-mile radius were forced to evacuate, with authorities telling people Friday they would not be allowed to return until Tuesday at earliest. A dusk-to-dawn curfew was imposed within two miles of the wreck for fear that cool night air would cause the chlorine to settle close to the ground.

With one ruptured tanker continuing to leak the deadly gas and the possibility of another leak from a second damaged tanker, rescue workers in protective suits searched for a worker still missing from the Avondale Mills (search) textile plant.

They also went door to door to find out whether there were any more deaths or injuries.

Monica Channey, 29, heard the boom at home when the trains collided but thought nothing of it at first. "It's always something with the trains or with the mill," she said.

But when authorities came to evacuate her and her 12-year-old son and 10-year-old daughter, she bundled the children up "like mummies."

Channey had a scarf covering her mouth but could still smell the chlorine. "The fumes were like 'whoosh' — a bad ammonia, stronger than any cleaning solution," she said. "It took my breath away."

The crash happened about 2:40 a.m. when a Norfolk Southern freight train carrying 42 cars struck a parked train at a crossing next to the plant, where 400 workers were on the night shift making denim and other fabrics.

"I saw a green mist coming toward me," machine operator Rodney Johnson told the Aiken Standard. "I stepped up to see what it was and ran to my supervisor. He said to get them out."

Johnson said he piled co-workers in his truck and drove to a hospital.

"It tore me all up," Johnson said. "My eyes burned and lungs hurt. I couldn't breathe at all. All I could think about was breathing and getting to rescue."

Mill spokesman Stephen Felker Jr. said some mill workers acted almost as emergency crews, alerting supervisors to an overwhelming bleach smell and urging other workers to get away. "Dozens and dozens of heroes were made," he said.

Volunteer Fire Chief Phil Napier met up with two members of the train crew after getting the train wreck call. As the men spoke, one told Napier he was having trouble breathing, then collapsed. That was when the smell hit the fire chief, who had no protective gear.

"I had to drive off and leave him on the ground," Napier said Friday, his bloodshot eyes starting to fill with tears.

Federal officials were investigating the cause of the wreck, but most officials were kept out of the area because of the toxic gas.

Sheriff's Lt. Michael Frank said 30 percent to 40 percent of the contents remained in the leaking tank, which can carry up to 90 tons of liquid chlorine under pressure. The material turns to gas when released.

Two nine-member crews were working around the clock to apply a steel patch over a hole in the tank about the size of a fist, Frank said. He said it could take up to a week to remove the chlorine in that tank and in two other railroad tankers.

In June 2004 in Texas, the collision of two freight trains near San Antonio released a chlorine cloud that left a conductor and two nearby residents dead.

Eight people were killed in February 1978 when a cloud of chlorine gas floated over a highway from a ruptured tank car after a freight train derailed near Youngstown, Fla.