COLUMBIA, S.C. (AP) -- Investigators wearing protective suits and oxygen tanks on Saturday searched the dense, swampy woods where a factory worker disappeared after a train wreck caused one of the nation's deadliest chemical spills in years.
Crews also worked to patch a hole in the train car that was carrying chlorine gas when the wreck occurred early Thursday in Graniteville, about 10 miles from the Georgia state line.
Eight people were killed and more than 250 were sickened by the toxic vapors, which descended on neighboring homes in a greenish-yellow fog.
Thom Berry, spokesman for the state Department of Health and Environmental Control, said crews would remove chlorine from two additional railroad tankers in the next couple days.
More than 5,400 residents have been forced to evacuate their homes and will not be permitted to return until Tuesday at the earliest, officials said.
The National Transportation Safety Board is investigating what caused the freight train carrying 42 cars to collide with a parked train at a crossing next to the plant, where 400 workers were on the night shift making denim and other fabrics.
The search for the missing factory worker was concentrated on the woods behind the Avondale Mills textile plant, where five workers died after being overcome by the fumes. Authorities believe the man, whose identity has not been released, could have followed several other workers who ran toward the woods to escape the vapors.
Berry said thick underbrush was hampering the search.
"There is a fear that vegetation could tear the protective suits that the searchers are wearing," he said. "They're having to be very, very careful."
State and federal environmental officials have conducted air quality tests since the crash and found either low levels of chlorine or none within blocks of the site. Levels at the crash site were higher.
Norfolk Southern has paid for hotels rooms and given $100 Wal-Mart gift cards or checks to people forced to evacuate. Berry said 12 people have defied the order and remained home.