PLUM BOROUGH, Pa. – (WPXI) -Four people are dead in an explosion in Plum Borough that destroyed three homes and damaged at least a dozen more. One more person is unaccounted for. One house was completely leveled with debris spilling onto the lawn. Officials say three people were hurt in the explosion. One person remains in the hospital in critical condition. Two others who were taken to the hospital in stable condition have since been released. According to officials, the explosion happened at around 10:23 a.m. on Rustic Ridge Drive and Brookside Drive. Crews at the scene saw one house completely leveled and debris pouring onto the lawn and street. Officials said first responders arrived at the scene and reported that people were trapped under debris from what appeared to be one house exploding. Multiple other houses were damaged with windows blown out by the explosion. In total, three structures were destroyed and at least a dozen others were damaged in some way, officials said. 18 different fire companies responded to the scene as well as Allegheny County Emergency Management officials, Allegheny County Fire Marshals, and water tankers from Allegheny and Westmoreland counties. There’s currently no word on what caused the explosion. Plum Borough on Facebook asked the public to stay away from the area and let the response team work. Plum Borough also said Renton Fire station is open if anyone needs refuge, food, water or a place to stay.