IOWA CITY, Iowa (AP) _ Five explosions rocked a chemical storage and pipeline station this morning, blasting out flames higher than nearby farmhouses. No one was injured.

''Each one was louder than the one before,'' said Mike Stevens, who lives about two miles from the blast site. He said the resulting fire sounded ''like a jet plane taking off.''

Six nearby homes were evacuated as a precaution after the blasts at the Mid-America Pipeline Co. plant in a rural area six miles east of Iowa City.

The fire was under control before noon, less than than two hours after it was reported, said Rick Neal at Mid-America headquarters in Tulsa, Okla.

There was no word on what caused the explosions. ''Once we can approach the site, we'll try to determine what happened and begin to make repairs,'' Neal said.

The fire was fueled by either an ethane-propane mix that is used as a building block for mixtures in the petrochemical industry or a liquefied petroleum gas, he said.

''At this point, we don't know which was involved,'' he said.

Neal said there was no concern about toxic fumes.

The explosion involved a pumping unit at the storage and transmission facility. Chemicals are stored there until they can be moved out through pipelines.

Neal said 36 people are assigned to the plant but he didn't know how many people were working at the time of the blast.

The pipeline company has had two fires and explosions in the area in recent years. In 1989, an electrical problem touched off a blast and fire. In 1987, a pipeline fire burned for nearly two weeks, feeding on liquid chemicals stored in a 14.7-million-gallon reservoir 710 feet below ground.

Mid-America has about 10,000 miles of pipeline throughout the country.

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