WEST READING, Pa. — Four people have been confirmed dead and three others remain unaccounted for following an explosion Friday at a chocolate factory in Pennsylvania.

West Reading's police chief said a fourth person was found dead under debris early Sunday at the R.M. Palmer Co. plant where the last erupted just before 5 p.m. Friday.

Rescue crews are using heavy equipment to pull debris from the site. Borough Fire Chief Chad Moyer said Saturday night that the chance of finding survivors was “decreasing rapidly” but Mayor Samantha Kaag said called it “a hold out for hope" to get answers for people. Investigators are still trying to determine the cause of the blast.