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 pm and used loudspeakers to tell the crowd to disperse or risk arrest, tear gas or the use of force, the Daily Camera reported.
The crowd dispersed around 9:30 pm, police said.
“Detectives are going to review all the clues we have to identify and arrest those responsible for this reprehensible and unacceptable behavior,” said Chief Maris Herold in a departmental post.
CNN contacted the Boulder police for comment.
The university called the meeting “unacceptable and irresponsible” and said it was aware of reports of “violence against police”.
“Any student found to be responsible for being involved in acts of violence against law enforcement officials or other first respondents will be removed from CU Boulder and not reinstated,” the university said in a statement.
The big meeting came a day after Colorado Governor Jared Polis extended the term of the state’s Covid-19 mask, which has been in effect since July 2020. Nearly 6,000 people died in Colorado due to Covid-19, according to with data from Johns Hopkins University.