By Tom Breen
The Associated Press

INSTITUTE, West Virginia — A chemical plant explosion rocked an area west of Charleston, hurling a fireball hundreds of feet (meters) into the air, killing one worker and injuring a second.

The explosion at the Bayer CropScience plant, which could be felt miles (kilometers) away, happened about 10:25 p.m. Thursday. State Department of Environmental Protection spokeswoman Kathy Cosco said the primary chemical involved, methyl isobutyl ketone, is highly flammable but not especially toxic.

Air monitoring found no sign of chemical exposure, either on or off the site about 10 miles (16 kilometers) west of Charleston, Bayer said.

The plant also produces methyl isocyanate, which killed at least 15,000 people in a leak in Bhopal, India, in 1984. Kanawha County Emergency Management Director Dale Petry said that chemical is stored in steel-wrapped underground containers located far from the blast site.

"They have a lot of chemicals at the plant and they do take great steps to protect them," said Joe Thornton, spokesman for the state Department of Military Affairs and Public Safety. "I think everything that can be done to protect those chemicals is being done, and I think the public at large is safe."

The explosion occurred in a section of the plant where waste products are treated before disposal, Bayer spokesman Mike Wey said. The unit had been closed for maintenance and was restarted earlier in the week, he said.

A worker who had been counted as missing was killed in the explosion, Petry said Friday.

Wey said the injured worker suffered burns and was transferred to a Pittsburgh hospital. A company emergency responder was treated at the plant infirmary for heat stress, Wey said.

Six other workers who normally work at the unit were not injured, Wey said.

Emergency crews extinguished the fire at about 2 a.m. Friday, Bayer said.

"Our thoughts and prayers are with the families of these employees during this very difficult time," Bayer said in a statement issued Friday morning.

"This is a very sad day for the Institute site family," the statement added.

Bayer said the cause of the explosion has not been determined. The unit was shut down and will not be restarted until the company determines that it can be safely operated.

Inspectors from the U.S. Occupational Safety and Health Administration were at the site Friday morning, Bayer spokesman Nick Crosby said Friday.

Methyl isobutyl ketone and another solvent in the unit, hexane, are used to produce the insecticide Larvin, which is made only at the Institute plant. The accident is expected to create a shortage of Larvin, which has seen growing demand from the global agricultural economy, Crosby said.

Residents miles (kilometers) away from the facility reported hearing the explosion.

West Virginia State University Police Department patrolman Robert Flinn said he felt the blast as he was sitting in his cruiser on the school's campus near the plant.

"Our back was turned, and it was like somebody shined a giant spotlight on us," he said.

Warne Ferguson lives less than a mile (1.6 kilometers) from the plant and the explosion shook his house.

"It scared my wife to death," said 81-year-old Ferguson. "I thought my house was falling down on top of me. That's how hard the vibration was."

Crosby said the company received several reports of broken windows from nearby residents.

Bayer CropScience is headquartered in Monheim, Germany.