Protesters gathered again on the streets of Ferguson, Missouri late Tuesday to voice anger about the shooting death of an unarmed black teenager by a white police officer.
The marches appeared to be peaceful, following a night of violent protests during which police arrested 78 people, including several journalists.
Ferguson, a community populated mainly by blacks, has been hit by street protests punctuated by looting and clashes with police every night since 18-year-old Michael Brown was killed on August 9.
Earlier Tuesday, U.S. Attorney General Eric Holder promised the people of Ferguson a "full, fair and independent" investigation into the shooting of Brown. Holder will be in the St. Louis suburb Wednesday to meet with community leaders, FBI investigators and federal civil rights officials.
A grand jury is expected to begin hearing evidence in the case on Wednesday.
In a videotaped message Tuesday, Missouri Governor Jay Nixon said a "vigorous prosecution" must now be pursued. He called for justice for Brown's family.
In a message published in the St. Louis Post-Dispatch newspaper, Holder said the full resources of the Justice Department are committed to the investigation.
He said, however, the town must see an end to violence and that the riots and looting in reaction to the shooting undermine justice.
The mayor of a U.S. town where police and protesters have clashed for 10 days following the fatal shooting of an unarmed black teen by a white policeman says there "is not a racial divide in the city of Ferguson."
Mayor James Knowles told U.S. TV channel MSNBC on Tuesday that the town of 22,000 people in the state of Missouri has been a "model for the region" as it changed from a majority white population to predominantly black.
The comments come after a third tumultuous night on the streets of Ferguson, which has seen ongoing protests since a police officer killed 18-year-old Michael Brown on August 9.
Seventy-eight civilians - including protesters and members of the press - were arrested Monday night and Tuesday morning in Ferguson after a day of peaceful protests. Initial reports indicated 31 arrests had been made.
St. Louis shooting
Meanwhile, police in St. Louis, Missouri have shot dead a man armed with a knife near the site of violent protests against the police shooting death of an unarmed black teenager August 9.
Police say the suspect in Tuesday's shooting allegedly stole merchandise from a food store.
He apparently challenged officers to shoot him and approached them with a knife. Police fired when he refused to drop it.
In Ferguson, Maria Chappelle-Nadal, who represents the town in the Missouri legislature, told CNN on Tuesday that peaceful protests would continue until charges were filed against the shooter.
"The demonstrations are going to continue until there's an arrest, until this officer is on leave without pay," said the state senator.
Nearly all of those arrested in the last day are charged with failing to disperse when police requested a crowd of roughly 200 people leave.
Outside agitators blamed
Most are not Ferguson residents, but many are from the area. Officials repeatedly have blamed protesters from out of state for violent acts during nighttime demonstrations.
Brown's death has sparked allegations of systemic discrimination against minorities and a nationwide debate on race in the U.S.
A poll conducted over the weekend and released Monday by the Washington-based Pew Research Center shows 80 percent of African-Americans believe Brown's death raises important issues about race, compared to 37 percent of whites.
The survey also found that while 65 percent of black respondents believe the police went too far in responding to the shooting, that number plummets to 33 percent among the white population.
Police fired stun grenades and tear gas at crowds, as demonstrators lobbed firebombs and bottles at heavily armored police.
Officers say they came under heavy attack, but did not shoot their weapons. Two people were reported wounded by shots from within the crowd. Many people appeared to be defying orders from police to disperse.
National Guard troops that arrived earlier Monday to strengthen police forces could be seen on the fringes of the gathering.
President weighs in
Monday, U.S. President Barack Obama said the actions of a "small minority" of demonstrators engaging in violence on the town's streets was heightening tensions.
He also said there was no justification for the use of excessive force by police, or any action that denies the rights of peaceful protesters.
An independent autopsy requested by Brown's family showed he was shot at least six times, including two bullets to his head.
Attorneys for Brown's family said the autopsy shows the unarmed black teen was "trying to surrender" when Officer Darren Wilson fatally shot him. Two other autopsies have been commissioned.
Wilson is on paid administrative leave during the investigation.