By KARMA ALLEN, ABC News

(MILWAUKEE) — Protesters took to the streets in Wisconsin on Wednesday after the Milwaukee County district attorney announced he would not press charges against the police officer who fatally shot a Black teenager outside of a mall earlier this year.

Alvin Cole, 17, was fatally shot by Wauwatosa Officer Joseph Mensah on Feb. 2, the third fatal shooting by Mensah in the past five years, Milwaukee ABC affiliate WISN reported. The prior shootings were ruled justified, but local civil rights activists have advocated for the officer’s firing.

Despite not pressing charges, the report did call for Mensah’s firing by the police department.

Wauwatosa Mayor Dennis McBride issued a statement immediately after the announcement and urged residents to remain calm after crowds gathered near the Milwaukee County Courthouse.

“Given recent events in Kenosha, Louisville, and other cities around the country, it should be clear that we all must do everything we can to keep our community peaceful. Violence is not the answer; it only impoverishes communities and brings more pain and despair,” McBride said in the statement.

“I ask all people, regardless of their viewpoints, to remain peaceful and calm as we work our way through this difficult time,” he added. “We all must keep each other safe.”

City officials implemented a 7 p.m. nightly curfew beginning Wednesday. Residents were asked to stay home and gas stations were ordered to close.

Wisconsin Gov. Tony Evers also mobilized the state’s National Guard to support in the hours leading up to the announcement in case of possible protest.

He said his office approved a request from local authorities for assistance and mobilized troops this week in advance of the anticipated decision.

“One of our core missions in the Wisconsin National Guard is to serve our fellow citizens and preserve public safety,” Maj. Gen. Paul Knapp, commander of the Wisconsin National Guard, said in a statement ahead of the decision. “Our Citizen Soldiers and Airmen live and work in the same communities all across Wisconsin, and we’re well-trained and prepared to assist our neighbors in any way we can.”

Wauwatosa police said Cole fired a gun at officers before his death, but an attorney for Cole’s family denied those claims, citing video evidence and witness statements.

Family members admitted that he had a gun, but said he never pointed it police.

The decision not to press charges comes amid ongoing demonstrations around the country against police brutality in the wake of several officer-involved shooting deaths involving Black victims, many of them unarmed.

The police shooting of Jacob Blake on Aug. 23 in Kenosha, Wisconsin, less than an hour south of Wauwatosa, triggered violent protests and calls for police reform. National Guard troops were also called in to Kenosha to deal with the demonstrations.

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