A skateboarding event adjacent to Dolores Park turned ugly Tuesday night, when police officers seeking to end the proceedings and event participants faced off.

KTVU reports that "hundreds" of people were watching skateboarders as they rode down Dolores Street between 18th and 21st Streets at around 7:11 p.m. Tuesday night.

"The skateboarders were being towed up the hill by vehicles and then riding down the hill on the boards, some performing tricks on the way down," NBC Bay Area reports.

The event echoed a similar one a year ago, dubbed The Hill Bomb, although police did not involve themselves in that one.

πŸ†πŸ†πŸ†πŸ†

A post shared by @lauriemurr on

According to San Francisco Police Department spokesperson Officer Grace Gatpandan, who spoke with the LA Times, police were called to the area to aid a skateboarder injured during the event. However, "the crowd did not allow the officers to tend to a person in the street with a head injury," NBC Bay Area reports.

Gatpandan tells the Chron that in addition to the injury, area "residents were calling in to complain of disruption and an inability to use all of the street."

"While the rider was being treated," the LA Times writes, "another skateboarder raced down the pavement and collided with a police sergeant before striking and flying over a patrol car parked toward the bottom of the hill."

You can see video of that fall here, which was characterized by some witnesses as the skateboarder being shoved by a police officer into the vehicle:

The LA Times reports that following that crash, onlookers "became hostile and more officers were called to the scene to gain control of the crowd spilling into the street."

(Note re the tweet above: That's not a shotgun -- the red butt and barrel is an indication that it's a so-called "bean bag gun.")

A witness tells KTVU that "he saw 'dozens and dozens' of cops, some of whom were using bean bag guns to disperse the crowd. There was a lot of 'chanting' and "jeering," he said. 'And skateboarders were everywhere.'"

According to NBC, the melee continued for at least an hour, as "skaters shouted and threw objects such as bottles."

"Police described the scene as a hostile environment," they write, "but one skateboarder who didn't want to be identified claims officers overreacted."

Mission Local reports that "some in the crowd began chanting 'f**k the police' and acted aggressively, said witnesses. At one point, a witness reported that a skateboarder ran into a parked police car and that the window of another police vehicle had been broken. Another person said a skater had 'shoulder-checked' an officer, pushing him into the patrol car."

According to the LA Times, "Vandals tagged two police cruisers with graffiti and smashed one of their windows."

No arrests were made during the incident, Gatpandan says.

Reports on the number of people injured vary, with the Chron reporting that two skateboarders β€” a man and a woman β€” as well as the police officer involved in the collision with the skateboarder were hurt at the scene. According to NBC Bay Area, "multiple skateboarders were taken to hospitals with head injuries" and the injured officer was also hospitalized.

According to Mission Local and ABC 7, the injured male skateboarder was Jake Phelps, the editor of Thrasher magazine.

As noted by Hoodline, Tuesday's event was likely "the second annual running of The Hill Bomb" skating event. Last year's went off without incident, as you can see here.

Mission Local described the event as one "which skaters ride down the hill at Dolores Street, and later partake in a race for a cash prize." However, "one skater at the scene said the race itself never happened," they report.

β€œCops came for obvious reasons" and thwarted the race, a bystanding skater told Mission Local. β€œLook at how dangerous it is. β€œ

β€œWe literally shut down Dolores Street,” a 22-year-old skater from San Francisco named Pete told the Chron. β€œThey (police) were doing their job. That doesn’t mean we always agree with it."

β€œIt got very very serious very fast. Then the cops got involved and the skaters got mad.”

Skaters vs SFPD right now in Dolores. Race to riot unfortunately fast. 😒 #sfpd #unnecessaryforce #thrasher

A post shared by Regina Marie (@reginastarkeys) on