SMITH TOWNSHIP, Pa. — Four people are hospitalized after an explosion at a plant in Smith Township Thursday evening. It happened at the Langeloth Metallurgical Plant. Smith Township officials confirmed there was an explosion. It reportedly happened while a tanker was transporting chemicals. Those injured include the driver of that truck and three other plant employees. There is no word on their identities or conditions. The Department of Environmental Protection and the Environmental Protection Agency have been called in to investigate. Officials say there was no threat to the public. Residents in nearby homes reported some damage to their homes. The plant is reportedly shut down.