DARLINGTON, Pa. — A husband and wife were killed Tuesday in an early-morning house explosion Tuesday in western Pennsylvania.The couple were inside the ranch-style home when the blast occurred about 4 a.m. in South Beaver Township, a rural area about 40 miles northwest of Pittsburgh, police said. The two were identified as 74-year-old Ray Trautvetter and 69-year-old Janet Trautvetter.Fire crews extinguished the blaze after they were initially kept away because of smaller explosions that police believe was ammunition going off. The fire marshal is investigating the cause.Officer Jesse Richman said the home used propane for fuel and police believe the explosion "probably is going to be gas-related."Family papers and fragments of the home were blown all along the small country road."It's just heartbreaking seeing their personal artifacts scattered everywhere," neighbor Stefanie Sergi, 37, told the Pittsburgh Post-Gazette.Mark Plevel?,?? 38, described the ??pair as good neighbors who brought him a cake when he moved in ?across the street ?five years ago.The Beaver County Coroner's Office said autopsies were planned for Tuesday.