They said the crash happened just before 10 p.m. in the area of Park and Cedar streets.
The unidentified victim was rushed to a nearby hospital but is expected to survive his injuries. Police say he suffered serious head trauma and broken bones.
"All of a sudden I see a guy lying on the ground look like he got hit," said Ratana Ross, who was working in a nearby liquor store and heard the impact. "He looked terrible. We literally thought at the time that he was gone. It was scary to see how he looked at that moment but we started seeing him breathing and then we started calling 911."
They said the victim was walking south on Park Street when he was hit by a three wheeled motorcycle heading west in the eastbound travel lane. Police said the motorcycle took off south on Washington Street.
The incident was captured on police surveillance video.
Police said they're looking for a six-foot tall bald light-skinned Hispanic man wearing a black vest, red hood and blue jeans driving a gray Polaris Slingshot motorcycle.