On Sunday, police violently broke up a peaceful protest in downtown Albuquerque, New Mexico, with tear gas and arrests. Hundreds of people had come out to protest against the recent slaying of a mentally ill homeless man by police, as well as the sharp escalation of police violence over the past four years.

The protest began around noon downtown when over 500 protesters converged at the Albuquerque Police Department (APD) headquarters. The protesters marched through the city, stopping at the City Hall to hear speeches from families who have had family members killed by the APD’s violence.

Protesters had been outraged by a video that showed police officers killing James Boyd, a homeless man with mental illness. The police deployed their elite Repeat Offender Project Team to deal with Boyd, who was delusional and trying to convince police that he was a high-ranking officer in the defense department and should not be searched.

After a standoff, Boyd agreed to go with the police and be searched. As he turned around to collect his things, the police shot a concussion grenade at Boyd and unleashed a K-9 attack dog on him. Boyd, frightened, turned around and brandished a small knife. Police then used their military grade assault-rifles and shot Boyd multiple times with live ammunition.

On the ground, seriously injured from multiple gunshot wounds, Boyd moaned, “Please don’t hurt me… I can’t move.” Police continued to yell at him and then proceeded to fire multiple “bean bag” shots before firing a real bullet. The K-9 dog was then unleashed again. Boyd died later in the hospital. At no point were the police, standing far away from Boyd, in any danger of being killed, let alone injured.

A 23-year-old protester, Alexander Sidertis, told AP that he was out protesting because he was “fed up” with the police’s abuse of the citizenry. He told the news agency that the situation “has reached a boiling point, and people just can’t take it anymore.”

Another protester, Justin Wagner, told the local KOB 4 news station that “there has been excessive force … and I think something has to be done.” He denounced the police chief for “justifying” the killing of Boyd.

The protesters marched throughout the downtown area for about eight hours. The Albuquerque Journal reports that the police told the crowd, as it sat near the APD headquarters, that their assembly was “unlawful.” The police proceeded to equip themselves with batons, riot shields, and gas masks.

After a tense standoff, protesters decided to move on and walk through the downtown area toward the University of New Mexico (UNM). Angry protesters were trailed by the police force as they made their way toward the university.

After night fell, protesters, in smaller numbers, stopped at a corner of the UNM campus near an APD substation. Here, the police confronted the protesters in full riot gear and back-up from an officer core on horseback, as well as the Bernalillo County Sheriff’s Office SWAT Team.

Police fired tear gas canisters into the remaining group of protesters and began making arrests. A video from AP news shows one protester trying to escape police custody while being beaten with batons by multiple officers. Several protesters were arrested; however the exact number is currently unknown.

The police response was heavy and militarized. KOB 4 reported seeing multiple SWAT teams. The station’s video footage shows a group of police officers dressed in green army camouflage, riding an armored personal carrier in similar army camouflage.

Police complained that protesters had vandalized property with graffiti. The mayor, Richard Berry, stated that the protesters had descended into “mayhem.” He accused them of throwing rocks against the police, and one of climbing up a traffic signal. Referring to the police, he said “the professionalism these men and women are showing is extraordinary.”

Since 2010, the APD has been involved in 37 shootings, 23 of them fatal. By comparison, from 2005 to 2010 the APD was involved in 14 shootings, nine of them fatal. Just 10 days after Boyd was murdered, another man was killed by the police. The police claimed they had been shot at.

Peter Simonson, the executive director of the ACLU in New Mexico, told AP that the police worked inside a “deeply rooted culture of the ability to use force with impunity.” He continued “over and over, what we’ve seen, people who are mentally ill, when they are confronted by the APD, they end up dead… there is a sense in the community that APD is out of control and there is no city leadership willing to step in and take responsibility.”