An explosion and fire that killed a family of four in northeast Ohio Monday night was arson, and possibly a murder-suicide, a medical examiner said.

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

The fire and explosion shook homes throughout the neighborhood. 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.

The Associated Press contributed to this report.