Gunman kills NY ex-girlfriend’s husband, child in attack near Montana’s Glacier National Park

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A man drove his vehicle into a family as they walked near Glacier National Park, then got out and began shooting at them with a shotgun, killing one man and mortally wounding a toddler before one of the victims managed to kill the assailant after he ran out of ammunition, authorities said Tuesday.

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

The assailant, Derick Amos Madden, 37, had mental health issues and had been in a prior relationship with Christina Siau, 30, who killed him, according to the Glacier County Sheriff’s Office.

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

Grinnell Glacier in northern Montana. 

Grinnell Glacier in northern Montana.  (Marli Miller/UCG/Universal Images Group via Getty Images)

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As members of the family tried to run, Madden 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.

After running out of ammunition, Madden used a knife to attack and critically wound Christina Siau, but she fought back and fatally wounded Madden, who died at the scene, authorities said.

Two minor children who were present were able to run away and escaped injury.

McKenzie Siau was later pronounced dead at the Indian Health Service hospital in Browning. Christy and Christina Siau were flown to a hospital with critical injuries.

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Authorities were still trying to determine if Madden, originally from Goldsby, Oklahoma, had legally obtained the shotgun.

The sheriff’s office described it as an “isolated…incident with a clear nexus between the victims and Madden” and said the investigation was continuing. It was not clear what provoked Sunday’s attack beyond the prior relationship between Madden and Christina Siau.

Local authorities did not know of any previous interactions that Madden had with law enforcement. He had been working recently in East Glacier, a tourist town and gateway to the mountains in Glacier National Park, according to Jody Hickey, a spokesperson for Glacier County Sheriff Vernon “Napi” Billedeaux.

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Christina Siau is originally from New York and has been living in East Glacier, where her family was visiting, Hickey said.

Christy Siau is a former bookkeeper for the American Baptist Churches of New York State, according to a social media posting by the organization. She is described as “a long time and beloved member” of the organization’s staff in a statement from Executive Minister Rev. James Kelsey.

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Christy and David Siau were also active in the First Baptist Church of Hoosick Falls, New York, Kelsey said.