SAN FRANCISCO (KRON) — A renegade skateboard competition down San Francisco’s Dolores Street turned ugly on Tuesday night after a skateboarder crashed into a cop.

Both the skateboarder and the police officer were injured in the collision.

And then, the crowd went rowdy because some believe the officer was out of line.

KRON4 spoke to one man who caught the moment of impact on video.

“You kind of see a train wreck about to happen,” Travis Knapp-Prasek said.

Knapp-Prasek was at the bottom of the Dolores Street Hill filming the skateboarding contest when the collision happened.

Police were there responding to assist another skateboarder who had been injured in the unpermitted event.

The skateboarders kept bombing down the hill and several were allowed to go through, but then, one cop on the scene moved into the path of one oncoming skater.

And that sent the skater into and then over the police cruiser, and then he landed down hard on the asphalt.

Some are saying the cop clotheslined the skateboarder intentionally.

“He put himself right into the path of that skater and held his ground, and he could’ve easily stepped away, and it would have been OK,” Knappe said.

That skateboarder, identified by a friend as Anthony, reportedly suffered a broken ankle, tore a ligament in his knee, and sprained some fingers.

While skateboarders are reviewing videos of the crash from different perspectives being posted online, an SFPD spokesman says they are too, and so far say it’s unclear what the video shows.

They are investigating the incident and will be reviewing police body cam video as well.

Police say after the crash, several bottles were thrown at the officers by people in the crowd, and they had to take a defensive line around the area and close some streets as a safety precaution.

But no one was arrested.

Police say the sergeant seen in the video was also injured in the crash and transported to the hospital where he was treated and released with non-life-threatening injuries.WHAT OTHERS ARE CLICKING ON:

 >> MORE TOP STORIES