In a chilling incident on Halloween night, a Colorado art teacher is accused of a fatal stabbing spree, allegedly using a “buck knife” crafted from an animal antler. The attack resulted in the death of a man and left two women injured, according to police reports.

Officers discovered 33-year-old Matthew Regnier from Colorado Springs “completely naked and covered in blood,” clutching a 2-year-old child when they responded to a call in the 1400 block of El Paso Street just before midnight on Friday, as detailed in an arrest affidavit obtained by Law&Crime.

That evening, Colorado Springs Police received several reports of a domestic disturbance. Upon arrival, Regnier allegedly informed them that he had recorded the incident and the events leading up to it in “selfie mode” on his cellphone. During subsequent police interviews, he claimed he acted in self-defense, as stated in the affidavit.

The affidavit further reveals that Regnier described the situation as a “three on one” attack, alleging that one individual tried to bite his finger, another attempted to strangle him, and a third tried to mutilate him.

Regnier stated that during this alleged assault, he reached into a closet, seized a “buck knife,” and “defended himself,” according to the affidavit.

The male victim, who is the aforementioned child’s uncle, died early Saturday morning after being rushed to a local hospital. The female victims both survived the alleged attack. The victims’ names are redacted from the affidavit and their relation to Regnier is unclear.

One of the women allegedly told police that Regnier was keeping her and the other woman away from the child after changing their diaper. Regnier admitted to cops that he didn’t have a good reason for why the trio would attack him, according to the affidavit.

In the cellphone video that Regnier captured, he can be seen repeatedly holding the camera in “selfie mode” while one of the female victims was behind him on a bed, her arm seemingly around his neck, according to the affidavit. “Matthew was observed screaming about being choked and not being able to breathe, but repeatedly escaped from the supposed strangulation,” the document alleges.

Regnier can be heard screaming “something about his testicles” before he begins to repeatedly stab the woman, according to police. Regnier was “completely naked and … covered in blood” during the assault, the affidavit says, noting how he allegedly began stabbing the other female victim as well.

The male victim entered the bedroom after hearing the women screaming and was immediately attacked by Regnier, according to cops. Regnier’s cellphone video captures audio and video of the attack.

“Women are heard screaming as Matthew is observed repeatedly raising the large fixed blade knife and plunging it in the directions of [the man’s] head and body,” the affidavit says.

Police say they found the knife that Regnier used inside of the residence.

“The handle of the blade appears to be made from the antler of a deer or other game animal,” the affidavit alleges. “The knife [appeared] to be consistent with the décor of the residence, which included several animal skins and mounted skulls.”

Neighbors told local ABC affiliate KRDO that they saw Regnier outside the home handing out candy earlier in the night. Local officials confirmed to Law&Crime that Regnier is a former art teacher at the charter school Monument Academy who had his employment terminated over the weekend following his arrest.

The school district says he served as both an educator and a coach with the junior varsity soccer team at Palmer Ridge High School.

Regnier was taken into custody and charged with murder, attempted murder and assault. He was being held without bail at the El Paso County Jail with his first court appearance scheduled for Nov. 10.