What began as a largely peaceful demonstration against police brutality in Albuquerque on Sunday afternoon was abruptly ended soon after midnight as security forces fired tear gas against protesters.

Local outrage was sparked after James M. Boyd — a homeless, mentally ill man — was shot dead by police in the Sandia foothills on March 16. The incident was followed by the fatal shooting of a man in a public housing complex; however, in that case authorities argued that officers were responding to initial shots fired by the suspect.

Police in the city have long been accused of using excessive force against residents. According to statistics compiled by the Associated Press, the city’s police department has been involved in 37 shootings, 23 of them fatal, in the past four years.

Last week, international hacktivist collective Anonymous released a video promising to retaliate against Albuquerque police and encouraged locals to protest against the department’s actions.

According to the Albuquerque Journal, the department’s website was breached and down for several hours on Sunday.

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