The arrest of a man at Chicano Park Thursday sparked an hours-long protest outside the doors of the San Diego County Jail downtown.
Alvarez, 22, is a member of the Brown Berets of Aztlan, a group that observes police activity at Chicano Park, according to the page.
Video obtained by NBC 7 shows the moment officers took Alvarez to the ground, and several witnesses can be heard saying that the arrest was unwarranted.
The San Diego Police Department said the incident started when 35-year-old Georgina Mercado interfered with an officer and sergeant making a traffic stop.
Mercado was taken into custody and officers tried to contact someone to release her three children, ages 8, 7 and 4.
SDPD said Alvarez arrived at the scene with another female and they said they would take the children, but Alvarez, wearing a bandana that covered his face, refused to identify himself to officers.
Police said the interaction with Alvarez escalated to the point where officers arrested him for interfering. Alvarez allegedly refused to put his hands behind his back during the arrest attempt, so officers struck him and forcefully moved his hands so they could handcuff him.
SDPD said an internal investigation will be conducted to determine whether officers used the appropriate amount of force and if policy and procedures were properly followed.
Protesters outside of the jail were heard yelling "Free Eddie Now" and other anti-police brutality chants.
According to the San Diego County Sheriff's Department, Alvarez faces a felony charge of obstructing and resisting an officer, and a misdemeanor for resisting an officer. He is being held on $20,000 bail.
No other information was available.
Editor's note: A previous version of this story incorrectly reported the protest took place outside of SDPD headquarters.