Nixon, who had declared a state of emergency for the town on Saturday and ordered that the streets be cleared for a curfew that ran from midnight to 5 a.m., said the National Guard would fall under the supervision of the Missouri Highway Patrol.
The deployment of the National Guard is the latest in a series of steps taken by authorities to end the looting and burning of stores that have punctuated protests since the shooting death of Michael Brown, 18, more than a week ago.
But retired local business owner Marshall Tucker said: “It ain’t getting no better with the National Guard coming in. That’ll be worse,” he said. “Tonight it’s going to get really sticky.”
As daylight was coming to an end on Monday, police with plastic handcuffs took positions and tried to clear a main thoroughfare where protests have taken place at night, directing crowds into designated protest areas.
Video from the scene showed one journalist, with cameras slung around his neck and his hands bound behind him, being led off by police. He was identified by colleagues as Getty photographer Scott Olson.
President Barack Obama said he told the governor that the National Guard use should be limited and urged healing instead of violence. Attorney General Eric Holder will travel to Ferguson on Wednesday, Obama added.
"While I understand the passions and the anger that arise over the death of Michael Brown, giving into that anger by looting or carrying guns, and even attacking the police only serves to raise tensions and stir chaos. It undermines rather than advancing justice," Obama told a news conference.
The president met with Holder on Monday to discuss the unrest. Holder said more than 40 FBI agents were canvassing Ferguson neighborhoods in an investigation that included federal and local officials.
"Moreover, at my direction, an additional medical examination is being performed on the body of Michael Brown," Holder said. Results of official autopsies by federal authorities and the county are pending.
An autopsy conducted on behalf of Brown’s family showed he was shot at least six times, including twice in the head. The path of one bullet indicates the 18-year-old may have been lowering his head in surrender when the fatal shot hit, according to Brown family attorney Daryl Parks.
Parks told a news conference one bullet hit Brown in the very top of his head and another shattered his right eye.
"His head was in a downward position," Parks said. "Given those kind of facts, this officer should have been arrested," Parks said.
There were no signs of struggle with the officer and no gunshot residue on the body.
According to police, the officer involved in the shooting said he fired initially after Brown reached into his police car.