NEW YORK (AFP) - Michael Brown, the unarmed black 18-year-old gunned down by a white officer in a suburb of St Louis, was shot at least six times, the New York Times reported late Sunday.

Brown was shot twice in the head and four times in the right arm, the newspaper reported, citing a preliminary private autopsy.

All the shots were fired into his front, the Times reported, citing Michael Baden, the former New York City chief medical examiner who conducted a separate autopsy at the family's request.

Brown's slaying on August 9 has triggered days of often violent protests in Ferguson, Missouri.

Tension has been high between the African-American residents of Ferguson and its mostly white police force.

Riot police late on Sunday hurled tear gas and marched with armoured vehicles to disperse a mob of mostly young people a few hours before a midnight (0500 GMT) curfew.

Some of the youths carried signs protesting police brutality, TV images showed. Many had their hands up in the air, and others taunted police and threw back tear gas canisters.

Police reportedly moved following gunfire and after being hit by Molotov cocktails.