WASHINGTON - President Barack Obama is ordering U.S. flags to be flown at half-staff to honor the victims of the shooting in California that left 14 people dead.

Obama says it's possible the massacre was related to terrorism but that authorities still don't know. He says it's possible it was workplace-related or that there were mixed motives.

Authorities say Syed Farook and his wife or fiancee killed 14 people at a social service center Wednesday before dying in a gunbattle with police. He fired on colleagues at a holiday gathering for county health employees.