AP

Published: Mar 31, 2014 10:17 AM EDT

ALBUQUERQUE, N.M. (AP) - Albuquerque's mayor said that a more than 10-hour protest over recent police shootings turned from peaceful into "mayhem," as officers in riot gear clashed with hundreds of protesters who blocked traffic, tried to get on freeways and shouted anti-police slogans.
    
Mayor Richard Berry said Sunday that one officer was injured, rocks were thrown and at one point protesters trapped police in a vehicle and tried to break the windows, the Albuquerque Journal reported. An Associated Press reporter saw gas canisters being thrown outside police headquarters and Albuquerque police and Bernalillo County sheriff's deputies charging at the protesters late Sunday, which mostly dispersed the crowds.
    
The number of protesters dwindled to fewer than 100 before midnight, and three or four people were arrested, the newspaper said.
    
Multiple messages left for the Police Department weren't immediately returned. Video by KRQE-TV showed people being led away in zip-tie restraints, but it's unclear if those people were arrested or if any protesters were injured.
    
"We respected their rights to protest, obviously," Berry said, "but what it appears we have at this time is individuals who weren't connected necessarily with the original protest. They've taken it far beyond a normal protest."
    
Protesters took to the streets in the early afternoon and stayed out late Sunday after authorities declared an unlawful assembly. People are angry over Albuquerque police's involvement in 37 shootings, 23 of them fatal since 2010. Critics say that's far too many for a department serving a city of about 555,000.
    
The protesters repeatedly marched the 2 miles from downtown Albuquerque to the University of New Mexico, holding signs protesting recent police shootings and often snarling traffic. Motorists honked, and supporters took photos with smartphones. Activists called on various city officials to resign, yelling late Sunday for the police chief to resign.
    
Justin Elder, 24, followed the protest as a passenger in a car and held a sign that read, "APD: Dressed To Kill."
    
"That's what this police force is about," Elder said.
    
Albuquerque police in riot gear and New Mexico State Police followed the marchers, and protesters were seen shouting epithets at officers. At one point, a protester climbed a tall street sign on the city's historic Route 66 and unsuccessfully attempted to bring it down.
    
Another protester, Alexander Siderits, 23, said he was participating because he was "fed up" with how police treat citizens. "It has reached a boiling point," he said, "and people just can't take it anymore."
    
The U.S. Justice Department has been investigating the police for more than a year, looking into complaints of civil rights violations and allegations of excessive use of force.
    
The gathering came days after a YouTube video emerged threatening retaliation for a recent deadly police shooting.
    
The video, which bore the logo of the computer hacking collective Anonymous, warned of a cyberattack on city websites and called for the protest march. Albuquerque police said their site had been breached early Sunday afternoon, but it was back by evening after being offline for hours.
    
Earlier Sunday, police spokesman Simon Drobik confirmed the disruption was due to a cyberattack and said investigators had not uncovered the source of the hack.
    
In the March 16 shooting that led to the YouTube posting Tuesday, a homeless man was killed in the foothills of the Sandia Mountains on the east side of Albuquerque. The shooting was captured on video and followed a long standoff. The FBI has opened an investigation into the shooting.
    
Last week, Albuquerque police fatally shot a man at a public housing complex. Authorities said he shot at officers before they returned fire.

(Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)