ST. PAUL, (AP) — The St. Paul Police Department has put an officer on leave while it investigates allegations that he made a post on Facebook urging drivers to run over protesters who rallied against the police killings of two black men in the Twin Cities last year.

The social media message said, “Run them over,” and told people how to avoid being charged with a crime if they struck someone during the Martin Luther King Day march and rally on a bridge linking St. Paul and Minneapolis.

Mayor Chris Coleman issued a statement saying he was “outraged and disgusted” and had directed officials to investigate.

“There is no room in the St. Paul Police Department for employees who threaten members of the public. If the allegation is true, we will take the strongest possible action allowed under law,” Coleman said.

According to a press release, a preview story about the protest on its Facebook page Friday night. The suspended officer allegedly posted a comment in reply, under a different name, that said: “Run them over. Keep traffic flowing and don’t slow down for any of these idiots who try and block the street.”  The post gave advice for avoiding charges and said anyone hit who sued would probably lose a jury trial.

Andrew Henderson, who runs the Minnesota Cop Block Facebook page, which focuses on police accountability, spotted the comment early Saturday and immediately reported it to police. He then filed an internal affairs complaint Sunday and turned over the evidence he believed showed that post really came from the officer.

The head of the internal affairs unit, Senior Cmdr. Shari Gray, said the department treated the post with “grave concern” because of the scheduled protest.

“If we needed to change tactics or operational security on the event, we needed to do it,” Gray said. “And then, two, make sure that if indeed this was one of our officers, that it’s addressed quickly.”