A skateboarder flipped over a police car after colliding with an officer at an event in San Francisco on July 11. There was a stand-off between police and attendees at the same event, and a number of boarders needed medical help following falls.

The officer and the man who collided with him were injured, according to reports. Ambulances were also called for a number of other boarders who took falls. The event was described by local press as an “informal competition.”

A number of police cars were also vandalized, according to reports and posts on social media. Credit: Facebook/Swarm Life via Storyful