LODGE GRASS, Mont. — The FBI says it's still trying to piece together what led to the fatal shooting of three people on Montana's Crow Reservation after the arrest of the suspected gunman Wednesday night in Washington state. Sheldon Bernard Chase was arrested without incident in Spokane, Wash. The FBI says he's suspected of using a rifle Tuesday afternoon to kill his grandmother, 80-year-old Gloria Sarah Goes Ahead Cummins; his cousin, 21-year-old Levon Driftwood; and her boyfriend, 20-year-old Rueben Jefferson.

Schools on reservations in southeastern Montana and western North Dakota were closed and residents stayed indoors for safety during the search for Chase.

The FBI's supervisor in Billings Eric Barnhart says Chase has a history of mental illness.

The shootings happened at Cummins' home about 10 miles outside Lodge Grass, a town of 500 people near the Wyoming border.