One man who ignored that advice today was chased down and arrested after San Francisco police spotted him urinating on a building, and now faces several possible felony charges, authorities said.

The incident began about 2:30 a.m. when Officers Michael Tursi and Phillip Gordon saw Desean Bailey, 21, of Brisbane urinating against the building at Sixth and Market streets, police said. The officers approached on foot, but Bailey ran away and threw a handgun on the sidewalk while doing so, authorities said.

Another officer responding to a call for backup saw Bailey about a block away and chased him down, police said.

Officers discovered that he was wearing a bullet-resistant vest and booked him on suspicion of being a felon in possession of body armor. He was also booked on suspicion of possessing a firearm, carrying a concealed firearm, resisting arrest and public urination.

E-mail Henry K. Lee at hlee@sfhcronicle.com.