FERGUSON, Mo. -- Missouri Gov. Jay Nixon ordered the National Guard to Ferguson early Monday, hours after police used tear gas to clear protesters off the streets following a week of demonstrations against the fatal police shooting of a black Missouri teenager.
In a statement, Nixon said the National Guard would help "in restoring peace and order" to the St. Louis suburb that has been filled almost nightly with angry, defiant crowds since 18-year-old Michael Brown was killed Aug. 9.
"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," Nixon said.
The latest confrontations came the same day Attorney General Eric Holder ordered a federal medical examiner to perform a third autopsy on Brown. A preliminary private autopsy found the unarmed teen was shot at least six times, including twice in the head. Results of a state-performed autopsy have not been released.
As night fell in Ferguson, another peaceful protest quickly deteriorated after marchers pushed toward one end of a street and authorities -- who said they were responding to reports of gunfire, looting, vandalism and protesters who hurled Molotov cocktails -- pushed them back by repeatedly firing tear gas. The streets were empty well before a state-imposed curfew took effect at midnight.
"Based on the conditions, I had no alternative but to elevate the level of response," said Capt. Ron Johnson of the Missouri Highway Patrol, who is command in Ferguson.
At least two people were wounded in shootings by civilians, he said.
The "extraordinary circumstances" surrounding Brown's death and a request by his family prompted the Justice Department's decision to conduct another autopsy, agency spokesman Brian Fallon said in a statement earlier Sunday. The results would be taken into account along with the state examination in the Justice Department's ongoing civil rights investigation into the shooting, Fallon said.
Dr. Michael Baden, a former New York City chief medical examiner who conducted the private autopsy for the Brown family, told The New York Times that one of the bullets entered the top of Brown's skull, suggesting his head was bent forward when he suffered a fatal injury.
Brown also was shot four times in the right arm, and all the bullets were fired into his front, Baden said.
A federally conducted autopsy "more closely focused on entry point of projectiles, defensive wounds and bruises" might help the Justice Department's investigation, said David Weinstein, a former federal prosecutor who supervised the criminal civil rights section of Miami's U.S. attorney's office. The move is "not that unusual," he added.
Federal authorities also want to calm any public fears that no action will be taken on the case, Weinstein said.
Sunday's clashes in Ferguson erupted three hours before the midnight curfew imposed by a day earlier by Nixon.
Officers in riot gear ordered all protesters to disperse. Many of the marchers retreated, but a group of about 100 stood defiantly about two blocks away until getting hit by another volley of tear gas.
Protesters laid a line of cinder blocks across the street near the QuikTrip convenience store that was burned down last week. It was an apparent attempt to block police vehicles, but the vehicles easily plowed through. Someone set a nearby trash bin on fire, and the crackle of gunfire could be heard from several blocks away.
Within two hours, most people had been cleared off West Florissant Avenue, one of the community's main thoroughfares. The streets remained quiet as the curfew began. It was to remain in effect until 5 a.m.
Earlier in the day, Johnson said he had met members of Brown's family and the experience "brought tears to my eyes and shame to my heart."
"When this is over," he told the crowd, "I'm going to go in my son's room. My black son, who wears his pants sagging, who wears his hat cocked to the side, got tattoos on his arms, but that's my baby."
Johnson added: "We all need to thank the Browns for Michael. Because Michael's going to make it better for our sons to be better black men."
The protests have been going on since Brown's death heightened racial tensions between the predominantly black community and the mostly white Ferguson Police Department, leading to several run-ins between police and protesters and prompting Missouri's governor to put the state highway patrol in charge of security.
Ferguson police waited six days to publicly reveal the name of the officer who shot Brown and documents alleging Brown robbed a convenience store shortly before he was killed. Police Chief Thomas Jackson said the officer did not know Brown was a robbery suspect when he encountered him walking in the street with a friend.
Nixon said Sunday on ABC's "This Week" that he was not aware the police were going to release surveillance video from the store where Brown is alleged to have stolen a $49 box of cigars.
"It's appeared to cast aspersions on a young man that was gunned down in the street. It made emotions raw," Nixon said.
Police have said little about the encounter between Brown and the officer, except to say that it involved a scuffle in which the officer was injured and Brown was shot. Witnesses say the teenager had his hands in the air as the officer fired multiple rounds.
The officer who shot Brown has been identified as Darren Wilson, a six-year police veteran who had no previous complaints against him. Wilson has been on paid administrative leave since the shooting, and the department has refused to say anything about his whereabouts. Associated Press reporters have been unable to contact him at any addresses or phone numbers listed under that name in the St. Louis area.
About 150 people gathered in St. Louis on Sunday to show support for Wilson. The crowd protested outside a TV station because it had broadcast from in front of the officer's home.
The station, KSDK, later apologized on its website. Others in the group, composed mostly of police and relatives of officers, carried signs urging people to wait for all the facts in the shooting case.
-- Associated Press writers Darlene Superville in Martha's Vineyard, Massachusetts, and Eric Tucker in Brewster, Massachusetts, contributed to this report.