A man who was vandalizing a sign at a Union Square intersection didn't take kindly to being interrupted Sunday, brutally beating the man who tried to stop him.

Police say the crime went down at 6:26 a.m. Sunday, at the intersection of Cyril Magnin and O'Farrell Streets, in the heart of Union Square.

Police say that a man in his 30s was observed vandalizing a sign in the area, When a 48-year-old man intervened to stop him, the suspect "immediately started punching [the victim's] face," a report from the San Francisco Police Department reads.

The victim was knocked to the ground and rendered unconscious in the assault, police say, waking up to find the beating continued with his attacker "kicking him on the back."

Eventually the violent vandal fled, police say.

The victim was transported to an area hospital for injuries police say are not life-threatening, including a laceration above his eyebrow and bruising to both his eyes.

The suspect remains at large, police say, and as of publication time no arrests have been made in the vandalism and attack.