ELIMSPORT — State police are tentatively blaming an improperly vented propane heater as the cause of death for five people who likely succumbed to carbon monoxide fumes while asleep in a small Pennsylvania cabin.

Trooper Angela Bieber at the state police barracks in Montoursville said Sunday morning that Lycoming County Coroner Charles Keissling is expected to confirm the cause of their deaths.

Authorities have said the two adults and three children had toxic levels of carbon monoxide in their blood when they were found Saturday. Bieber says there’s no indication they tried to escape and all five apparently died in their sleep.