BILLINGS, Mont. (AP) — A man drove his pickup truck into a family as they walked in a tourist village bordering Glacier National Park and opened fire with a shotgun, killing one man and mortally wounding a toddler who was in her mother’s arms before the mother’s sister-in-law managed to kill the assailant after he ran out of ammunition, authorities said.

Killed in the weekend attack on the Blackfeet Indian Reservation in northwestern Montana were David Siau, 39, of Syracuse, New York, and Siau’s 18-month-old daughter, McKenzie.

The assailant, Derick Amos Madden, 37, had been in a prior relationship with the woman who killed him and had mental health issues, the Glacier County Sheriff’s Office said Tuesday. Authorities did not say how he was killed.

Madden plowed his Toyota Tacoma into the Siau family just before 9 p.m. Sunday as they walked along the road in the small town of East Glacier Park, hitting some of them before crashing into a tree, the sheriff’s office said.

Madden got out and shot and killed David Siau and mortally wounded McKenzie. The young girl was being held by her mother, Christy Siau, 40, who was shot and wounded.

Madden then ran out of ammunition and used a knife to attack the sister-in-law, Christina Siau, 30, said Capt. Tom Seifert with the Glacier County Sheriff’s Office.