(CNN) -- Protesters took to St. Louis streets for a second night Thursday after an off-duty officer killed a teen who fired at him three times, authorities said.
Chants of "no justice, no peace" rang into the night as crowds rallied after the Wednesday evening shooting. "We pay you. You're our employees!" a protester shouted.
Police arrested eight people: five on accusations of unlawful assembly, two for alleged property damage and one on a marijuana possession charge, St. Louis police spokeswoman Schron Jackson said.
One officer suffered minor injuries and two police cruisers were damaged, Jackson said.
"I think the officers showed a tremendous amount of restraint," St. Louis Police Chief Sam Dotson told CNN affiliate KMOV.
Protesters also burned at least one American flag, CNN affiliate KSDK reported. That didn't go over well with some.
These protesters in Saint louis burning American flags makes me sick,brave men and women in uniform died for that flag,and they burn it?— allen (@AllenVA75) October 10, 2014
"These protesters in Saint louis burning American flags makes me sick," Twitter user AllenVA75 posted. "brave men and women in uniform died for that flag, and they burn it?"
But others defended the burning.
lmfao people really getting mad that they're burning the flag in St. Louis. not about the black teens that are dead, the burning flag— Monty (@PontifexMonty) October 10, 2014
Twitter user PontifexMonty said "people really getting mad that they're burning the flag in St. Louis. not about the black teens that are dead, the burning flag."
The teenager, Vonderrit Deondre Myers, was struck by seven or eight bullets, said Dr. Michael Graham, a St. Louis medical examiner
"All but one gunshot wound were to the lower extremities," Graham said. "The one fatal wound was to the head."
Police said the teen fired a pistol three times at an off-duty St. Louis officer who was wearing his uniform while moonlighting for a security company. The officer fired back 17 times, authorities said.
Myers and Brown were both 18, African-American and killed by white police officers. One big difference: Police said Brown was unarmed.
"It's a clear case of this young man being gunned down by an insensitive white officer who was off-duty," Akbar Muhammad, who also is a member of a coalition calling for the officer who shot Brown to be prosecuted, told CNN affiliate KTVI.
Neil Bruntrager, a lawyer for the St. Louis Police Officers' Association, dismissed accusations that 17 shots were excessive.
"When he uses deadly force, he uses deadly force until the threat is gone," he said on "Erin Burnett OutFront."
Without video of the incident or unbiased witnesses, the police and the public must rely on physical evidence, he said. A 9 mm pistol allegedly fired by Myers was found at the scene, police said. It was jammed, which shows that it had been fired, Bruntrager said.
But Van Jones, a civil rights activist and CNN contributor, said there's a lot of police mistrust after the Brown killing.
"You're seeing a wholesale breakdown of trust," he said.
The officer, a six-year veteran who has not been named, was placed on administrative leave. He served two tours of duty with the military in Iraq and was awarded a Bronze Star and a Purple Heart, Bruntrager said.
While on patrol, the officer saw three men run away as he approached, Dotson said. He chased them after one held up his pants in a way that made the officer believe he may be carrying a gun, Dotson said.
The officer tussled with one teen, who ran off, then turned around and fired at least three shots toward him, Dotson said.
The officer returned fire, killing the teen.
Additional marches are planned over the weekend around the St. Louis region, organizers said.
CNN's Shawn Nottingham contributed to this report.