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.

Four employees were hurt and taken to the Sewickley Hospital.

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

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