The US state of Missouri is sending the National Guard to the town of Ferguson as protests escalate over the police shooting of an unarmed black teenager.
Governor Jay Nixon signed an order to "help restore peace and order and to protect the citizens of Ferguson".
The decision was made as police clashed with angry crowds shortly before a second night under curfew began.
Police in Ferguson, a suburb of St Louis, said they came under attack and had "no alternative" but to respond.
Capt Ron Johnson said protesters had thrown Molotov cocktails and bottles at security forces, and set up barricades before the five-hour curfew began at midnight (05:00 GMT).
"For those who would claim that the curfew was what led to [the] violence, I will remind you this incident began three and a half hours before the curfew was to have started," he told journalists in Ferguson on Monday.
Officer Darren Wilson shot the teenager after reportedly stopping him for walking in the street, disrupting traffic.
The governor of Missouri has criticised police for releasing CCTV footage which apparently shows Brown stealing some hours before his death.
Nixon said the release of the footage "appeared to cast aspersions" on the dead man, saying "it made emotions raw".
VIDEO: Police fire smoke and tear gas canisters at protesters defying curfew in Ferguson: http://t.co/82yC9s7L0b— The Associated Press (@AP) August 17, 2014
But he also condemned the protesters: "These violent acts are a disservice to the family of Michael Brown and his memory and to the people of this community who yearn for justice to be served and to feel safe in their own homes."
A preliminary post-mortem examination by the St Louis County Medical Examiner's office on the day after Brown's death found he had been shot, police said, without disclosing how many times.
But a preliminary private post-mortem report has since revealed that he was shot at least six times, including twice in the head, the New York Times reports.
The bullets did not appear to have been fired from very close range due to the lack of gunpowder on the victim's body, forensic pathologist Michael Baden was quoted by the paper as saying.
He flew to Missouri on Sunday to conduct a separate autopsy at the request of the family.
Officials last week confirmed that the officer who shot Brown was a six-year police veteran with no previous complaints against him. He has been on paid administrative leave since the shooting.