A swarm of partygoers in Boulder caused “significant” property damage on the Pearl Street Mall Friday night and officials are working to identify those responsible, according to the City of Boulder.

Boulder police officers were sent to the 1100 block of Pearl Street around 9:30 p.m. after a report of approximately 200 unruly people. Within 90 minutes, the group had grown to between 1,000 and 2,000 people who were “hanging from light poles and trees, accessing rooftops and causing property damage to windows, tables, chairs and outdoor heating posts,” officials said in a release Saturday afternoon.

Authorities did not disclose an estimate on the amount of property damage.

Officials said due to the large number of partygoers, police responded with a large, uniformed presence and tried to disperse the crowd. During these efforts they noted many of the people were under the influence, but still responded to verbal commands.

As officials dispersed the crowd, police used drones as a response and documentation tool. Police said they’ll be using the footage to identify people committing crimes, according to the release.

“We recognize the negative impact a situation like this has on our local business community, which his already feeling significant pressure due to the pandemic,” said Boulder Deputy Police Chief Stephen Redfearn in a news release. “We will be using our investigative resources to demonstrate that there are consequences to destruction of property and other unlawful behavior.”

City officials did not release an estimated amount of property damage sustained.

There are some indications that some of the participants went to the area in response to a social media effort to resurrect the Pearl Street Mall Crawl, which has been discouraged by businesses and city officials in recent years due to safety and property damage concerns, officials said.

The incident happened while both the Boulder Police Department and University of Colorado Police Department had increased enforcement because of the Halloween weekend. This effort will continue through Monday, officials said.

The two departments are investigating the incident.

Police are asking students and residents to party responsibly this weekend, and discourage any unlawful behavior, said Redfearn.

“The police department supports safe, responsible gatherings,” Redfearn said. “What occurred on Pearl Street last night, however, posed significant danger to participants, resulted in unacceptable damage to property and required extensive police resources to address.”

Anyone who witnesses or experience property damage is asked to contact the Boulder Police Department at 3093-441-3333.