Missouri's governor announced Thursday that the state National Guard would begin a "systematic" withdrawal from Ferguson, the St. Louis suburb that has been rocked by unrest over the fatal police shooting of an unarmed African American man.

Gov. Jay Nixon's decision follows a quiet night in Ferguson, where tensions appear to have eased in the wake of a visit Wednesday by U.S. Attorney General Eric Holder, who promised a thorough federal investigation of the Aug. 9 death of 18-year-old Michael Brown.

"As we continue to see improvement, I have ordered the Missouri National Guard to begin a systematic process of withdrawing from the City of Ferguson," the governor said Thursday in a statement.

Nixon mobilized the Guard on Monday after an intensification in clashes between police and protesters in Ferguson, an escalation authorities largely attributed to the presence of elements from out of town.

The National Guard was given the specific assignment of protecting the law enforcement Unified Command Center in Ferguson, which had come under attack Sunday night.

Since the deployment of the Guard, "the situation has greatly improved with fewer incidents of outside instigators interfering with peaceful protestors, and fewer acts of violence," Nixon's office said.

Only seven of the 163 people arrested since the protests began were Ferguson residents, according to press accounts.

The unified command, comprising officers from the Missouri State Highway Patrol, St. Louis County, St. Louis City and other jurisdictions, "will continue its mission to respond appropriately to incidents of lawlessness while protecting the rights of all peaceful citizens," the governor's office said.

Holder's brief stay in Ferguson included sessions with community leaders, local elected officials and with FBI agents and other Justice Department personnel involved in the federal investigation of the Aug. 9 incident.

The attorney general also paid a call on the parents of Brown, who was shot six times by Ferguson police officer Darren Wilson, who is white.

Holder told community residents gathered at the Florissant Valley campus of St. Louis Community College that he had assigned the government's "most experienced agents and prosecutors" to the probe of Brown's death.

The African American attorney general said he hoped his visit would have "a calming effect" on Ferguson, a mainly black town of about 21,000 people. EFE