Missouri Governor Jay Nixon's move to bring in the guard troops follows his declaration on Saturday that the area was in a state of emergency and the setting of a curfew requiring the streets to be cleared after midnight.
President Barack Obama yesterday met Attorney General Eric Holder to discuss the Ferguson situation, his office said.
Both the US Department of Justice and St Louis County Police are investigating the shooting of 18-year-old Michael Brown.
Each night since the teenager was killed, protesters have been walking the streets in and around the neighbourhood where he was shot. The demonstrators have been holding signs, chanting slogans and calling for the arrest of 26-year-old Darren Wilson, the officer who shot Brown.
Schools in the area were closed yesterday because of the chaos in and around the town of roughly 21,000 mostly black residents.
Brown's mother Lesley McSpadden yesterday gave a television interview saying peace could be restored "with justice ... arresting this man and making him accountable for his action".Her family's lawyer, Benjamin Crump, said autopsy results that show Brown was shot six times, including twice in the head, were "very troubling".
"It's just not justified in any way, fashion or form to execute this child," Mr Crump said.