A police officer in Madison, Wisconsin killed a 19-year-old black man following an altercation, triggering an anti-brutality rally in the city. Dozens have taken to the streets chanting, “Black lives matter.”

The killing happened at around 6:30 pm on Friday. An officer was responding to reports of a man jumping in and out of traffic, creating a safety hazard, Police Chief Mike Koval reported.

The officer followed the suspect into an apartment and forced his way in because he heard a disturbance. In the ensuing fight the man was injured by gunfire, the chief said.

Koval stressed the officer immediately began to administer first aid, as did other officers who arrived at the scene. Nevertheless the man died in a local hospital.

Grandmother of Tony Robinson yells to police officers on #WillyStreet "You're not protecting us, you're killing us." pic.twitter.com/8dfsAG5xKb — Thomas Yonash (@thomasyonash) March 7, 2015

The police did not identify the gunshot victim, but his relatives said his name was Tony Robinson, a 2014 graduate of Sun Prairie High School, the Wisconsin State Journal reported.

The police said the man was suspected of a recent assault and battery. They said the preliminary finding at the scene “did not reflect [sic] a gun or anything of that nature that would have been used by the subject.”

Following the death, some 100 activists gathered at the scene as police blocked off the area. They chanted: “Black lives matter” prayed and drummed. Many of the activists then entered the Madison City County building, according to videos published on social media.

Robinson’s aunt, Lorien Carter, described her nephew as “gentle” and said, “he didn’t deserve” to be killed. She said his family encouraged peaceful protest.

Jack Spaulding, 17, said he was Robinson’s best friend and added he was “one of the happiest people I know.”

The Department of Justice’s Division of Criminal Investigation is investigating the shooting. A Madison law introduced in 2014 requires that all homicides involving police are looked into by an outside agency. The killing on Friday is the third since the law was adopted.

Crowd had moved to Wilson St entrance of #MadisonWI City Hall after #WillyStreet shooting. New info in video— pic.twitter.com/OhhqBAjROt" — Anonymous (@occupythemob) March 7, 2015

The death in Madison comes amid a period of keen public attention to cases of black people being killed by the police. The killing of a black teenager in Ferguson, Missouri, in 2014 triggered nationwide protest against police brutality and what many protesters see as racial bias against black minorities.

A federal investigation into Ferguson PD revealed a “toxic atmosphere” of mistrust between the St. Louis suburb police force and the predominantly black community. The DoJ is considering disbanding the department as one of the options for a planned reform.