LEETSDALE, Pa. (KDKA) – An explosion at the Leetsdale Industrial Park injured four people.

According to the Leetsdale Police, an explosion in the processing room of Hussey Copper happened around 5 a.m.

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Four employees were hurt and taken to the Sewickley Hospital.

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Their condition is unknown. The county fire marshall is investigating as the cause of the explosion is also unknown.

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Stay with KDKA.com for the latest on this developing story.