A man walking down a Richmond District sidewalk was knocked unconscious yesterday, by a fellow pedestrian who reportedly didn't even stop and check on the person he mowed down.

It was 4:45 Wednesday, police say, when a 60-year-old man walked down a sidewalk near the intersection of Third Avenue and Clement Street.

Suddenly, in what police are characterizing as an "aggravated assault," a man in his 30s ran straight into the pedestrian, knocking him to the ground.

The older man was rendered unconscious by the fall, according to the police. The person who struck him fled on foot, and hasn't been seen since.

In addition to being knocked out, the victim of the pedestrian-on-pedestrian collision suffered injuries to his eye. He was transported to San Francisco General for treatment, and is expected to survive.