A confrontation between skateboarders and police erupted in San Francisco Tuesday night, after a rider collided with a police cruiser.Hundreds gathered on Dolores Street for a “hill bombing” early in the evening, with crowds gathered to watch the skateboarders ride down the steep hill. After some were injured, ambulances were called to the scene and police officers arrived to break up the event, according to local reports.Tensions rose after a rider collided with a police vehicle, and some observers said an officer deliberately got in his way. Some of the onlookers fled the scene after this, but some stayed behind to confront the police. No arrests were reported, but two patrol cars were damaged.The officer and skateboarder involved in the collision were both taken to the hospital, along with two other people injured in separate falls during the event.