A man drove his vehicle into a family walking on a Montana road before opening fire on the group with a shotgun, killing a toddler and a 39-year-old man, authorities said Tuesday.
Two women in the group, including one who had previously been in a relationship with the suspect, were critically injured in the attack, the Glacier County Sheriff’s Office said.
One of the women, Christina Siau, 30, killed the suspect, Derick Madden, 37, after he attacked her with a knife, the Glacier County Sheriff’s Office said.
Christy Siau, 40, was also critically injured. She had been holding her daughter, McKenzie Siau, 1, who died of her injuries, the sheriff’s office said.
David Siau, 39, was also killed, the sheriff’s office said. He was McKenzie Siau’s father and husband to Christy Siau, NBC Montana reported.
Madden had previously been in a relationship with Christina Siau and was “suffering from mental health issues,” the sheriff’s office said, adding that the attack was “isolated to this incident with a clear nexus between the victims and Madden.”
“The investigation continues and detectives are working tirelessly to find all the details and circumstances surrounding this horrific event,” the sheriff’s said.
The attack occurred on Sunday night in East Glacier Park, just outside Glacier National Park on the Blackfeet Indian Reservation, the sheriff’s office said.
This article was originally published on NBCNews.com.