The 9 a.m. blast destroyed the home in Rose Township, 60 miles northeast of Pittsburgh. Investigators were still searching for a cause of the explosion Friday evening.
Killed were Charles F. Harper, 64, his wife, Dorothy, 53, and their grandchild, Bailey Harper.
Harper was the pastor of Seneca United Methodist Church in Venango County before retiring in the past year.
Autopsies were to be conducted Saturday.