The newspaper also reported that some in the crowd set off fireworks and overturned at least one car.
Police arrived on the scene shortly before 8:30 p.m. and used loudspeakers to tell the crowd to disperse or risk arrest, use tear gas or use force, Daily Camera reported.
The crowd dispersed around 9:30 p.m., police said.
“Detectives will review every lead we have to identify and arrest those responsible for this reprehensible and unacceptable behavior,” Chief Maris Herold said in a department post.
CNN has reached out to Boulder Police for comment.
The university called the meeting “unacceptable and irresponsible” and said it is aware of allegations of “violence against police officers.”
“Any student found responsible for having participated in acts of violence against the police or other first responders will be removed from CU Boulder and will not be readmitted,” the university said in a statement.
The big gathering came a day after Colorado Governor Jared Polis extended the mandate of the state’s Covid-19 mask, which has been in effect since July 2020. Nearly 6,000 people have died in Colorado due to Covid- 19, according to data from Johns Hopkins University. .