A medical examiner in Ohio says murder-suicide is one of the possibilities being looked at in a house explosion and fire that killed a married couple and their two daughters.

The Summit County medical examiner's chief investigator said Thursday that it could take weeks to make a ruling.

The state fire marshal's office said Wednesday that investigators determined arson was the cause of the fire and explosion that shook homes throughout the neighborhood southeast of Cleveland.

Authorities say Jeffrey and Cynthia Mather were killed, along with their daughters, 8-year-old Ruthie and 12-year-old Alyson.

The state fire marshal's office says they know what caused the fire, but they aren't releasing details while the investigation is ongoing.

Investigators say they've ruled out a natural gas leak.