Authorities promised to pursue criminal charges after a massive party near the University of Colorado in Boulder devolved into a violent confrontation with police that left three officers injured.

Hundreds of people flooded the streets in an area known as the Hill on Saturday night and when told to leave threw bottles, rocks and other objects at police and firefighters, police said.

At least one car was damaged when the mob flipped it over, and police brought in a SWAT team and used tear gas to break up the crowd that numbered 500 to 800 people at its peak, said Boulder police Chief Maris Herold.

Images shared by local media showed no social distancing and most without masks despite the coronavirus pandemic. Fireworks were set off in the middle of the street and a law enforcement armored vehicle and a fire truck were damaged, according to police and local media.

At one point Herold said a “tactical decision” was made to withdraw some officers when a group of about 100 people started to rush them. It took more than three hours to disperse the crowd, according to a timeline she provided.

Boulder County District Attorney Michael Dougherty described the rowdy behavior amid the coronavirus pandemic as “shameful.”

“I hear people refer to it as a party. I don’t regard flipping over a car as a party and I don’t regard people who throw bottles and rocks at firefighters and police as a party,” he said. “Those are criminal acts and will be treated as such.”

No arrests were made at the scene, police said.