Police are currently searching for a suspect, who is believed to have shot the man on the Morrison Bridge after a brief altercation.
"Preliminary information indicates that a suspect was in a vehicle on the bridge and there was a confrontation with someone in the protest," Portland police said in a statement. "The suspect got out of the vehicle and fired multiple shots injuring the victim."
Police described the suspect in a tweet as an "African-American male, late teens, 5'8", thin," who was wearing a "black dark hoodie and saggy blue jeans" at the time of the incident.
Authorities told NBC the victim is accepted to survive his injuries.
Protests against the president-elect have raged in the city since Thursday, and Portland police claim they turned violent not long after they began. According to a PPD Twitter account, Thursday night's protest saw protesters wielding bats and fire devices and launching projectiles at police, who later characterized the demonstration as a "riot."
Other cities across America, including Boston, Portland, Atlanta, Chicago and the District of Columbia, have seen protests in the wake of Trump's election, and are expected to continue to see them throughout the weekend.