Arvada Police officers look on as the hearse carrying the casket of fallen Officer Dillon Vakoff leaves his memorial service on Friday, Sept. 16, 2022, at Flatirons Community Church in Lafayette, Colo. Vakoff was fatally shot while trying to break up a large family disturbance earlier in the week, in Arvada. (Timothy Hurst/The Gazette via AP)

ARVADA — A man accused of killing a suburban Denver police officer who was responding to a family disturbance says he did not know law enforcement was at the scene when he started shooting, according to an arrest affidavit released Monday.

Sonny Almanza, 31, told investigators he thought he was shooting at a relative of the mother of his two children during a Sept. 11 fight but instead hit 27-year-old Arvada police officer Dillon Vakoff, KUSA-TV reported.

According to the affidavit, Almanza was involved in a domestic disturbance concerning his minor children and their mother, who he had broken up with two weeks earlier.

Authorities say Vakoff and his fellow officers were dispatched to check on the children’s well-being when they encountered the disturbance. Almanza is accused of opening fire, wounding a woman, at which point the officers returned fire. Almanza then shot and killed Vakoff, according to the affidavit.

Almanza faces several charges, including first-degree murder and attempted murder.

Vakoff is the second officer killed in the line of duty in as many years in Arvada. In 2021, Officer Gordon Beesley, 40, was shot and killed in an ambush by a gunman wielding an AR-style rifle.