What started as a traffic scrape escalated when an angry bicyclist slashed an off-duty Minneapolis police officer’s tires before being arrested on assault charges, authorities say.

The bizarre incident unfolded last Thursday as the off-duty officer was driving home from work, heading west on W. 35th Street in Minneapolis, according to charges filed this week in Hennepin County District Court.

According to the charges:

The bicyclist, John Sawchak, 46, suddenly pulled onto the street, forcing the officer to swerve out of the way.

A few blocks later, Sawchak pedaled up to the unnamed officer, who was by then parked near the intersection of W. 35th Street and Garfield Av. S. Sawchak abruptly stopped near the rear of the officer’s vehicle, nearly going over his handlebars.

The officer heard hissing and felt the vehicle list to the side. The officer got out of the car and found that Sawchak had slashed one of his tires.

The officer chased Sawchak and pulled him off his bike.

Sawchak began screaming “You tried to kill me, you tried to kill me!” as the officer pushed him against a nearby parked car. Sawchak then spun loose and faced the officer with a 4-inch knife in his hand, according to the complaint.

The cop stepped back and drew his badge and gun, identified himself as a police officer, and ordered Sawchak to drop the knife.

Sawchak refused and began screaming, “Help me, this guy has a gun. … Somebody call the police!” He continued to scream and flail the knife until the officer leveled the handgun at his chest and shouted at him again to drop the knife. Sawchak then said “OK” and threw the knife to the curb.

Sawchak was booked into the Hennepin County jail in lieu of $70,000 bail and later charged with second-degree assault.