WHEELING, Ill. (CBS) — Several people were taken to the hospital Saturday after a hazardous gas leak at a factory in Wheeling.

At 3:30 p.m., the Wheeling Fire Department arrived at Richelieu Foods, 120 W. Palatine Rd. They found 70 employees had been evacuated from the factory – and three were taken to local hospitals with minor injuries.

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The leak was identified as being anhydrous ammonia, used for refrigeration in food processing.

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The fire department then ventilated the factory, which is about 500,000 square feet.

The source of the leak had not been identified Saturday night.

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The Richelieu Foods factory makes frozen pizzas.

CBS 2 Chicago Staff