Blast at Ohio Plant Forces Evacuation : Explosion: At least one worker is killed and two are missing and presumed dead after nine-hour fire. The cause is unknown.

An explosion at a chemical plant sent flames shooting hundreds of feet into the air Friday and produced a mass of thick, black smoke that forced 1,700 people to flee.

One of the employees in the Shell Chemical Co. plant at the time was killed, the company said in a statement. Two others were missing late Friday and presumed dead.

Plant manager Arnie Dittmar would not identify the three, but said their families had been notified. No injuries were reported, officials said.

Fifty to 75 of the factory’s 480 employees were working at the time of the explosion, spokesman Mike White said.

By late afternoon the fire was brought under control and local residents were allowed to return to their homes as firefighers conducted precautionary detoxification procedures to assure they had no chemicals on their clothes or equipment. It was not known whether the smoke and fumes were toxic.

The plant produces a thermoplastic rubber used in automotive parts, footwear and adhesives.

The plant, along U.S. 50, is a complex of buildings covering about 15 acres, located about a mile from this Ohio River town of 6,800 people.

The fire began at about 6:30 a.m. in one building and spread to at least one tank, which collapsed, said Washington County Fire Capt. Chris Forshey. He said he did not know the tank’s contents.

The cause of the explosion was not immediately known. Residents 10 miles from the plant said they felt a jolt from the blast.

By early afternoon, flames were shooting 300 to 600 feet into the air, and the heat was so intense that firefighters had to retreat.

The fire required about 500 firefighters, and equipment was brought in from neighboring states. Firefighters battled the blaze for about nine hours before it was extinguished.

Two of the burning chemicals were petroleum-based solvents cyclohexane and styrene monomers, said Ohio Environmental Protection Agency spokesman Rob Berger.

Both are used in the production of plastics and can produce irritating or poisonous gases.

Authorities evacuated 15 homes in Porterfield, Ohio, five miles west of Belpre, and later ordered the evacuation of everyone within a one-mile radius of the plant.

A nearby portion of U.S. 50 was closed, and schools in the city and some surrounding areas canceled classes. The Coast Guard was advising commercial and recreational boaters to avoid the Ohio River at Belpre because of the smoke.