Protesters took to the streets of south St. Louis Wednesday night following the fatal shooting of an 18-year-old African American man by a 32-year old white police officer in the city’s Shaw neighborhood. In an early Thursday morning briefing, Police Chief Sam Dotson said the man fired three shots at the officer first. The officer, a six-year veteran of the department, returned fire 17 times.

According to police, the officer was off-duty and patrolling the neighborhood as an employee of a private security company when he drove past three men at about 7:30 p.m. Wednesday. As the officer drove past the group, one of the males began to run. When the officer made a U-turn, they fled, police said.

“One of them ran in a way that the officer believed that he was armed with a gun — holding his waist band, not running at full stride,” Dotson said, referring to the 18-year old.

The officer, who was wearing a Metropolitan Police Department uniform, drove through the streets after them, then left his car and chased the group on foot. One of the men then turned toward the officer and approached him “in an aggressive manner,” Dotson said. The 18-year-old and the officer got into a physical altercation.

Dotson said the man then ran up a hill and fired three times at the officer before the officer returned fire. Investigators recovered a 9mm Ruger at the scene, which Dotson said was used by the 18-year-old, whom he described as “no stranger to law enforcement.” Police said the weapon was reported stolen on Sept. 26.

“The suspect continued to pull the trigger on the gun … we learned that that gun had malfunctioned and it was jammed,” Dotson said.

The officer returned fire, killing the man. The 18-year old was identified as Vonderrit D. Myers Jr. by police.

The officer involved in the shooting worked for Hi-Tech Security, which employs several St. Louis police officers in secondary, “moonlighting” jobs. He was patrolling the neighborhood on behalf of that company, not the city’s Metropolitan Police Department.

St. Louis police said officers are permitted to be employed as security guards in uniform, while carrying their department issued weapons. Even when they are not on duty, the officer would “still has the same responsibilities and power to affect arrest and the officer operates in the capacity as a St. Louis Police Officer,” the department spokeswoman Schron Jackson said in a statement.

The officer — a six-year veteran of the force — has been placed on administrative leave.

Dotson announced the launch of an internal and criminal investigation.

“When the investigation is complete and during the investigation, in consultation with the circuit attorney’s office, we will present that case to them and ask them to review it to make a decision about the officer’s actions and if they were appropriate in that situation,” Dotson said.

Relatives quoted by local news organizations said the man had only a sandwich, not a weapon.

“He was unarmed,” Myers’ cousin, Teyonna Myers, told the St. Louis Post Dispatch. “He had a sandwich in his hand, and they thought it was a gun.”

Dotson said police were interviewing witnesses to get a firmer picture of what happened. In the police summary of the incident, the department refers to Myers as the “suspect” and the officer as the “victim.”

In the aftermath of the shooting, at least 200 people took to the streets, jeering at police and blocking traffic on Grand Boulevard.

There were no reports of injuries, though some police cars were damaged. Some chanted “hands up, don’t shoot,” the mantra of protesters in neighboring Ferguson, Mo., where and unarmed teen Michael Brown was shot and killed by a Ferguson police officer Aug. 9.

“I pray this is not another Mike Brown situation,” Sharon Norman, 50, told the paper. She was one of many who invoked the events in Ferguson.

St. Louis Alderman Stephen Conway, who represents the Shaw neighborhood, said he was “very concerned” about the activity in the streets, but believed the incident would be handled differently than the shooting in Ferguson.

“Chief Dotson has a fairly good reputation as being a straight shooter, honest, considerate,” Conway said in an interview. “I watched his police officers handling themselves admirably in the face of some serious yelling, screaming, kicking of their cars last night.”

Police reported no significant violence. There was one arrest of an unidentified individual for having a gun.

Myers lives about a block and a half away from where the incident occurred Conway said.

“Everybody has heartfelt sorrow for the family, and we feel bad,” Conway added.

Myers had been scheduled to stand trial in November for unlawful use of a weapon and resisting arrest charges related to an June incident in which he was a passenger in a car involved in a high-speed chase with police, according to the Post-Dispatch. After the car crashed, Myers reportedly exited the car and threw a loaded .380-caliber pistol into the sewer. He was later caught by police, the Post-Dispatch reported.

Here’s the briefing by Dotson:

[This post has been updated.]