An explosion followed by a house fire killed an Amish woman and her six children on Sunday morning in central Pennsylvania, authorities said. Pennsylvania State Police said the incident occurred in Lamar Township in Clinton County near Mill Hall.

Firefighters responding to a report of an explosion and fire found that seven people were trapped inside the home, according to the state police statement. The statement said the burning house was too dangerous for crews to conduct a search.

Police identified the victims as Sarah Stoltzfus, 34, and her six children, ranging in age from 3 to 11. The children included four sons, ages 11, 10, 5 and 3, and two daughters, ages 8 and 6, the authorities said. An online obituary posted by a local funeral home identified Stoltzfus as a member of the Old Order Amish Church community.

Pennsylvania State Police said the cause is under investigation. In the early investigation, police said a propane leak inside the home may have caused the explosion and fire, and they said exterior propane tanks did not explode and were not contributing factors.

Investigators also pointed to the speed at which the fire took over the home after the blast. Christina Duck, who told WNEP-TV she was eating breakfast when it began, said she heard an explosion and saw flames through the windows almost immediately. “And I heard a boom and I could feel it and I got up and looked out the window and I could see the flames through the windows and I come running outside and within a minute the whole house was completely engulfed,” Duck said.

Duck said she ran outside as the fire spread quickly and that by the time firefighters arrived, there was no chance to save the structure. “By the time firefighters got there, ‘there was no saving that house, it went up so fast,’” she said.

Local reporting showed video of members of the Amish community arriving at the scene to clean up and pay respects. The family had moved into the home only recently, Duck said, adding that she often saw the children outside playing.