DENVER (AP) — Dozens of armed “anarchists” descended on the Denver Police Headquarters late Saturday and damaged buildings, set fires and injured an officer, city officials said Sunday. A dozen people were arrested.

“I want to be clear, what we experienced last night was not a protest. It was anarchy," said Murphy Robinson, executive director of public safety. “The people that showed up last night — the anarchists that showed up last night — brought weapons to the table. They had guns, they brought explosives, axes, machetes and had one intent purpose and that was to harm our officers that were there to serve in the line of duty to protect our city.”

Fireworks were shot at officers, an American flag and a tree outside a courthouse were set ablaze, windows were shattered and fast-food restaurant was broken into during the unrest, news outlets reported.

One officer suffered a concussion and third-degree burns, said Police Chief Paul Pazen. The officer was expected to recovery, he said.

Robinson said he was lifting a jail inmate cap that was put in place to prevent the spread of COVID-19 to accommodate those arrested on Saturday and officials said they will look at state or federal laws to charge those who were arrested and will seek restitution for the damages.

People in the crowd said they were protesting for a variety of reasons — from efforts to defund the police department, to displeasure over the police response to a homeless camp last week, to the death of Elijah McClain — according to news outlets. McClain died after being stopped by police last year in the suburb of Aurora.

“The narrative that these anarchists are marching for justice of Black lives is frankly false,” said Robinson, who is Black. “The public needs to know that you do not represent us. Stop using the color of my skin as an excuse to tear up my city.”

Less-lethal munitions such as smoke and pepper balls were used to clear the crowd of 50 to 75 people, officials said.

“We're not going to stand for their anarchy, their chaos or their mindless destruction in our city," Mayor Michael B. Hancock said.