Protesters gathered in a St. Louis neighborhood late Wednesday after an off-duty police officer fatally shot an 18-year-old black man who police say opened fire on the officer during a foot pursuit.

St. Louis Police Chief Col. Sam Dotson said the 32-year-old unidentified officer, a six-year veteran of the force, was working for a private security company when he approached three men on the street.

"As he exited the car, the gentlemen took off running. He was able to follow one of them before he lost him and then found him again as the guy jumped out of some bushes across the street," Lt. Col. Alfred Adkins said. "The officer approached, they got into a struggle, they ended up into a gangway, at which time the young man pulled a weapon and shots were fired. The officer returned fire and unfortunately the young man was killed."

The way that one of the men ran — grabbing at his waistband, slightly lopsided — indicated that he was carrying a weapon, so the officer chased him, Dotson said.

Ballistic evidence recovered from the scene indicates that the man fired three rounds at the officer before his weapon jammed, Dotson said, adding that the gun was also recovered.

The officer fired 17 shots, Dotson said. He said he didn't know how many of those shots hit the suspect or why the officer fired that many shots.

"An investigation will decide if the officer's behavior was appropriate," he said.

A state senator and other black leaders in St. Louis called on the Justice Department Thursday to investigate the fatal shooting.

The St. Louis Post-Dispatch reported that people claiming to be relatives of the victim identified him as 18-year-old Vonderrit Myers, Jr. The teenager's mother, Syreeta Myers, told The Associated Press by phone Thursday that her son was holding a sandwich when the officer killed him Wednesday night.

Hours after the shooting, a crowd gathered at the scene. Some people shouted "Hands up, don't shoot" in reference to the fatal shooting in August of an unarmed black man, Michael Brown, by a white police officer. That shooting in Ferguson led to weeks of sometimes violent unrest in the St. Louis suburb. Officer Darren Wilson has not been charged in the shooting.

Dotson said some in the crowd late Wednesday shouted obscenities toward officers and damaged police cars. Officers, however, "showed great restraint," he said.

"Any police officer use of force certainly will draw attention," Dotson said.

KTVI reported that some protesters were seen hitting police vehicles and shots were heard in the area. The station also reported that police largely backed off to give the protesters space.

No demonstrators were arrested and by 1 a.m. Thursday the crowd had largely dispersed.

Dotson said he wasn't aware of any video of the shooting.

"We want to be open and transparent and as thorough as we possibly can," Dotson said.

It was the third fatal police-involved shooting in the St. Louis area since Brown's death. On Aug. 19, Kajieme Powell, 25, was shot by St. Louis city officers after moving toward them with a knife while telling them, "Shoot me now. Kill me now." Both officers fired six shots each. Powell died at the scene.

On Sept. 17, officers shot and killed a 42-year-old man in the St. Louis County town of Jennings after the suspect allegedly slammed his vehicle into two police vehicles before pointing a rifle at officers.

The Associated Press contributed to this report.

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