A 20-year-old St. Louis man is dead after attempting to force his way into the home of an off-duty police officer following a heated Facebook debate concerning the Black Lives Matter movement.

According to St. Louis County police, Tyler Gebhard rang the doorbell of the unidentified officer’s Lakeshire, Missouri home around 6 p.m. Saturday evening. When he was denied entry by the officer’s wife, Gebhard reportedly hurled a 50-pound concrete planter through a rear window of the residence and attempted to enter. He was subsequently shot and killed by the officer.

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Authorities said Gebhard was acquainted with the St. Louis cop but had made threats against the officer and his family prior to Saturday’s deadly encounter. The former high school football star befriended the officer at a local church, the St. Louis Post-Dispatch reports.

According to St. Louis County Police Chief Jon Belmar, the unnamed officer’s wife, mother-in-law and kids were home at the time of the shooting and attempted to escape through a bedroom window. He described the situation as a “very difficult position to be in.”

“I don’t think the officer had a choice — I honestly don’t,” Belmar said.

Gebhard, who is biracial, suffered two gunshot wounds to the chest.

As authorities continue to investigate, it’s still unclear how an online debate concerning police brutality and the Black Lives Matter movement quickly boiled over into a deadly attempted home invasion. According to Gebhard’s uncle, his nephew outwardly supported the anti-police brutality cause but wasn’t an active participant in the protest movement.

The St. Louis Post-Dispatch reports numerous posts on Gebhard’s Facebook page about the recent deaths of five Dallas police officers and the shooting deaths of Black men at the hands of white officers. While some of his posts warned of “race wars,” others promoted peace and understanding between Black and white Americans.