CINCINNATI, JULY 19 -- Explosions ripped through a chemical plant today, killing one person, injuring as many as 63 others and shattering windows in houses and businesses up to a quarter-mile away, authorities said.

Fire Chief Bill Miller had said there were reports of a second death, but later said it could not be confirmed. He said up to 63 people were injured, but hospitals said they were treating 56. Four were critically injured.

The two explosions, which shook buildings more than a mile away, ignited a fire that took 2 1/2 hours to contain sufficiently for firefighters to enter the four-story brick building.

The blast sent fireballs 50 feet into the sky. A column of thick, black smoke poured from the building into the surrounding residential neighborhood. Some of the injured were cut by shattered glass at a supermarket.

About 1,000 people were evacuated from houses in the neighboring incorporated area of Norwood for the night while authorities checked for structural damage, said Norwood safety director Darryll Maxwell. He said six homes had been declared uninhabitable.

Air tests performed by the Ohio Environmental Protection Agency around the plant found no toxic gases in the smoke, Miller said.

About 200 people work at the BASF Corp. plant, which makes linings for cans and coatings for paper cups. The building contained about 50 chemicals, including explosive solvents and varnishes, workers at the scene said.

Kenneth D. Diedenhofer, a BASF production manager, said the company was investigating the possibility of a "pressure buildup" of chemicals in equipment that was being cleaned.

Dan Delaney, who works near the plant, said he saw a huge ball of fire and smoke from his office window. "Shortly thereafter, everybody was running down the street, out of the building to get out, sort of in a panic, just getting out of there as fast as they could," Delaney said.

"Police and firemen are all around, fighting the blaze," he said. "They just keep getting small explosions and more fireballs shooting up in the air."

Ken Kinderman, 29, a materials handler at the factory, said he was walking out of a locker room in an adjacent building when the explosion occurred.

"I opened the door and when the explosion hit, it threw me back through the locker room," Kinderman said. He said he was cut on his back and arms.

He said the building where the explosion occurred was used for handling solvents and varnishes.

"I saw the flames shoot from the other building into mine. The whole back of my building is gone," Kinderman said.

The dead man was identified by authorities as Lawrence H. Krechting, 58, a BASF employee.

Diedenhofer, the production manager, said he was in a lab overlooking the resin development building when the first explosion occurred about 2:15 p.m. "It blew out all the windows. The whole resin building was engulfed in flames," he said. "I couldn't get in to help anyone. I saw one person hanging on to the building. I was able to get him off."