(KGW/NBC News) Authorities say an Oregon man killed four members of his family in what investigators describe as a "horrific scene."

Clackamas County Sheriff's investigators say 42-year-old Mark Leo Gregory Gago killed his parents, his girlfriend and their infant daughter late Saturday night inside their Woodburn home.

The victims are identified as 9-month-old Olivia Gago, 31-year-old Shaina Sweitzer, 66-year-old Jerry Bremer and 64-year-old Pamela Bremer.

Deputies shot Gago after they arrived to find him attacking his girlfriend's 8-year-old daughter from a previous relationship.

Investigators believe Gago used a variety of weapons in the attacks including a sword and an ax..

"Every investigator that I've talked to that has been inside the residence, they can not explain how horrific the scene is, it's a traumatic scene just to see, so this is a tough one," said Clackamas County Sheriff's Sgt. Brian Jensen.

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