SYRACUSE, N.Y. (WSYR) — On Tuesday, a father from Pompey, New York and his 18-month-old daughter were on vacation in Montana when they were shot and killed. The child’s aunt managed to kill the assailant after he ran out of ammunition, authorities said.

Just a few days after the murder, John Siau, the father and grandfather of the victims, shared a video asking people to not “harbor anger.”

“As I have talked to each of my children — we have a very large family — I’ve said to them: grieve, be sad, but don’t harbor anger about what is happening … because what we have seen is the result of someone who has harbored anger his entire life,” John Siau shared.

He later went on to share an important line of prayer that he hopes everyone can think about: “Forgive us our trespasses, as we forgive those who trespass against us.”

“Certainly, the Siau family has had terrible trespasses committed against us,” said Siau. “But our goal is to forgive.”

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

The assailant, Derick Amos Madden, 37, from Goldsby, Oklahoma,had been in a prior relationship with David’s sister Christina Siau, 30, the Glacier County Sheriff’s Office said.

Madden plowed a Toyota Tacoma onto a sidewalk and into the Siau family just before 9 p.m. Sunday as they walked in the small town of East Glacier Park, hitting some of them before crashing into a tree, the sheriff’s office said. Glacier County Sheriff’s Office said Madden had previous mental health issues.

Madden got out and shot and killed David Siau and mortally wounded McKenzie. The child was being held by her mother, Christy Siau, 40, who was also shot and wounded as she tried to run away.

Madden then ran out of ammunition and used a knife to attack Christy’s sister-in-law Christina Siau. After a fight, Christina fatally wounded Madden, who officials said died at the scene.

Capt. Tom Seifert did not release further details about how Christina Siau killed Madden.

“She fought back and she won,” Seifert said.

The community is raising money to support the family through GoFundMe and a fund set up through the family’s church.

The Associated Press contributed to this report.