The gruesome scene played out at a home in Hackensack, N.J., where 43-year-old Wayne Carter allegedly barricaded himself in on Sunday, NBC New York reported.
Officers got a call that morning when a witness said Carter was threatening to harm himself with a knife. Two cops responded, kicked in the door and found Carter in the corner, the station reported.
Carter allegedly ignored officers' orders to put down the knife, and instead began stabbing himself in the abdomen, neck and legs.
An attempt to pepper spray the bleeding man had no effect, the Associated Press reported.
That's when Carter -- disemboweled but responsive -- reportedly threw bits of his skin and intestines at the officers.
They decided to retreat and call in the Bergen County SWAT team, Hackensack police Lt. John Heinemann told reporters. The team was able to subdue Carter and get him to a hospital, where he remained in critical condition on Monday.
Heinemann said he believes that drugs or mental illness may have led to the horrific incident, but those details haven't been confirmed.
No charges have yet been filed due to the unusual nature of the incident.