Officials scrambled to head off renewed anger Wednesday after an armed black teenager was shot dead by a white officer in a St Louis suburb, insisting the use of force was justified.

Officials scrambled to head off renewed anger Wednesday after an armed black teenager was shot dead by a white officer in a St Louis suburb, insisting the use of force was justified.

The killing took place late Tuesday at a gas station in Berkeley, near Ferguson, Missouri -- ground zero of a new protest movement over police killing of black suspects -- and triggered immediate protests.

Nationwide protests were sparked after unarmed black teenager Michael Brown was shot dead by a white officer in Ferguson, a mainly African American town with a mostly white police force.

After several weeks, demonstrations gained momentum in reaction to several other killings of black suspects by police, including that of Eric Garner, who died in a chokehold in New York last July.

Separate grand juries is St Louis and New York failed to indict officers in either the Brown and Garner cases, sparking allegations the justice system is weighted against black victims of police abuse.

But officials in Ferguson's neighboring suburb Berkeley said Tuesday's shooting should not be compared to the previous cases, and said the officer was acting in self-defense.

"You couldn't even compare this with Ferguson or the Garner case in New York," Berkeley Mayor Theodore Hoskins said.

"Everybody don't die the same. Some people die because the policeman initiated it some people die because they initiated it, And at this point, our review indicates that the police did not initiate this."

He told reporters most city officials and police officers in Berkeley -- a town of 9,000 which is 85 percent black -- are African American.

"Our police officers are more sensitive and it's because of the black and white relationship, it's because they interact, so you get a better understanding, that's why I believe we are different than the city of Ferguson."

He said both St Louis County and local Berkeley police were conducting independent investigations of the incident, which was captured on surveillance video.