Albuquerque police face off with protesters Sunday, March 30, 2014, in downtown Albuquerque, N.M. during a protest against recent police shootings. Hundreds of protesters marched past riot police in Albuquerque on Sunday, days after a YouTube video emerged threatening retaliation for a recent deadly police shooting.

ALBUQUERQUE, N.M. - Hundreds of protesters marched past riot police in Albuquerque on Sunday, blocking traffic, trying to get on freeways and shouting anti-police slogans 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 visible late in the afternoon after being offline for hours.

The department didn't return multiple phone messages left Sunday evening. Earlier, police spokesman Simon Drobik confirmed the disruption was due to a cyberattack and said investigators had not uncovered the source of the hack.

Meanwhile, 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.

Albuquerque police in riot gear and New Mexico State Police followed the marchers, but they had not made any arrests by early evening. Protesters were seen shouting epithets at officers, who announced over a loudspeaker that the protest was an unlawful assembly.

The protest comes as Albuquerque police have been involved 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.

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.

As the crowds arrived back at the university late Sunday, one protester climbed a tall street sign on the city's historic Route 66 and unsuccessfully attempted to bring it down.

Erin Thompson, spokeswoman for the mayor, said, "Mayor (Richard) Berry is actively tracking the situation in consultation with Chief (Gorden) Eden and command staff and has been all afternoon and throughout the evening." The mayor was holding a press conference later Sunday.

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 department for more than a year, looking into complaints of civil rights violations and allegations of excessive use of force.

Last week, Albuquerque police fatally shot a man at a public housing complex. Authorities said he shot at officers before they returned fire.

In the shooting on March 16 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.

Anonymous, a loosely organized worldwide hacking group, has been blamed for breaking into confidential information and defacing websites.

The FBI has opened an investigation into the shooting.