Toddler and her father killed in Montana after a man drove into a family and started shooting, officials say

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.

After Madden "purposely" drove his vehicle into the group, he crashed into a tree and emerged with a shotgun, the sheriff’s office said.

“Madden began shooting at the same victims he had just hit or attempted to hit,” the sheriff’s office said.

After fatally wounding David Siau, he “continued to shoot at the victims" as they ran away, the sheriff’s office said.

“During this attack Christina fought for her life and despite receiving critical injuries, fatally wounded Madden,” the sheriff’s office said.

The sheriff’s office did not say how he was killed.

David Siau and Madden were pronounced dead at the scene. McKenzie Siau died at Indiana Health Service in Browning, 13 miles away, the sheriff’s office said.

Two other children who were with the group fled and were not injured, the sheriff’s office said.

Christina Siau, originally from New York, had been living in East Glacier, where her family was visiting. Madden, of Oklahoma, had been working in the Montana town, according to the Associated Press.

Christy Siau was a former book keeper for the American Baptist Churches of New York State, the AP reported. She was described as “a long time and beloved member” of the organization’s staff in a statement from Executive Minister Rev. James Kelsey.