Violence erupted in St. Louis overnight in the wake of the fatal shooting by police of an African-American teenager they say fired at an officer three times. Protesters blocked traffic and broke windows.

The St. Louis Post-Dispatch said one officer was injured when he fell to the ground with a protester, who was maced by another officer. KMOV-TV reported some protesters were pepper-sprayed near the intersection of Grand Boulevard and Arsenal Street in the Shaw neighborhood of south St. Louis. A police car’s driver-side window was also allegedly smashed, and a pharmacy’s glass door was broken.

However, St. Louis Police Chief Sam Dotson told reporters the situation was under control and both protesters and police were dispersing.

Police wearing riot gear form a line in Shaw. (AP Photo/Jeff Roberson)

The protests follow the fatal shooting Wednesday of an 18-year-old African American man by an off-duty 32-year old white police officer who was working for a private security firm in the city’s Shaw neighborhood.

After observing what police called suspicious behavior by three men, the officer turned around. The men fled and the officer pursued one of them on foot. 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. Investigators recovered a 9mm Ruger at the scene, which Dotson said was used by the 18-year-old, Vonderrit Myers Jr., whom he described as “no stranger to law enforcement.”

“The only thing he was armed with was a sandwich,” a family spokesman, pastor Willie Kilpatrick, said at a prayer vigil last night, according to KSDK-TV. ” … We stand tonight with this mother and father, we stand with them because parents should not have to bury their children.”

The disturbances followed the vigil, according to police. The crowd of protesters, estimated at a few hundred, shouted abuse at police in riot gear who stood silently by, according to news reports. 

Protesters cheer after blocking an intersection after a vigil. (Reuters)

Dotson reported two arrests during the night. He said the tensest moment was when a crowd surrounded a police car and tried to break windows. At some point, someone in the crowd hurled a knife at an officer, who was uninjured, he said. But he praised much of the crowed for ultimately dispersing peacefully.

“We stabilized the situation and now we’re de-escalating it,” he told reporters.

Myers was scheduled to stand trial in November for unlawful use of a weapon and resisting arrest charges related to a 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.