A St. Louis man is facing charges after police said he spit on and threw a rock at an off-duty police officer Wednesday.

According to charging documents, Demetrius Washington, 25, assaulted the off-duty officer on the 7000 block of Pennsylvania Avenue even after being told the man was an officer.

At around 4:15 p.m. Wednesday, Washington walked up to the officer and asked to shake his hand. The officer told Washington he did not like what Washington and others were doing in the neighborhood, and he would be keeping an eye out.

Washington then spit on him, at which time, he told Washington he was a police officer. Washington spit on him again and ran off.

The officer started chasing the man, but soon gave up the chase. As he was walking away, Washington threw a rock that hit the officer in the head.

Washington is facing a second- and third-degree count of assault on a law enforcement officer.