NEW ORLEANS: New Orleans police are investigating a drive-by shooting that killed a man and an 18-year-old woman and wounded five other people, three of them children.

The shooting happened around 8 p.m. Sunday in the city's Lower 9th Ward, a neighborhood that was ravaged by Hurricane Katrina and has struggled with crime.

Officer Frank Robertson says a woman and two boys aged 2 and 4, were in critical condition and a 13-year-old girl and a 37-year-old woman were in stable condition.

Robertson says all the victims were in front of a house when a dark car occupied by several men drove up, opened fire and sped off. Police have not release very many details of the shooting or a description of the suspects.

In a separate incident in the city of St. Louis, protesters clashed with police and looted stores after an officer shot dead an unarmed black teen, local media reported Monday.

Police armed with clubs hurled tear gas and deployed officers with dogs to curb the violence that erupted late Sunday in Ferguson, in the Midwestern state of Missouri, reports said.

But local law enforcement officers were quickly overwhelmed and had to urgently call for backup from nearby communities, according to KSDK TV 5.

Video posted by the St. Louis Post-Dispatch showed a gas station convenience store plundered and set on fire.

Looters also raided a Walmart and several other smaller stores, and set fires elsewhere, the newspaper reported.

The violence broke out after large crowds of mostly African-American protesters gathered Sunday for a vigil at the spot where police shot and killed 18-year-old Michael Brown a day earlier.

Details of Brown's death differ. A witness identified as Dorian Johnson told KMOV News 4 that he was walking with Brown when a police officer confronted them and drew his weapon.

The officer shot Brown, who "turned around and put his hands in the air," Johnson said. "He started to get down and the officer still approached with his weapon drawn and fired several more shots."

St. Louis County Police Chief Jon Belmar, however, said at a televised Sunday news conference that Brown was killed after physically assaulting a police officer and struggling to get his weapon.

Belmar did not say whether the officer was white.