Mom and six children, ages 3 to 11, were killed after a house explosion in Lamar Township, Pennsylvania, early Sunday. Firefighters responded around 8:30 a.m., but the flames were too intense to enter the home and reach those trapped inside.

Authorities are investigating the cause, with a possible propane leak being considered. Officials say external propane tanks did not explode, as state police and fire investigators continue examining the scene.