Hundreds of demonstrators stood inches from officers in riot gear late Friday at the start of what was expected to be a weekend of protests over the 2-month-old death of Michael Brown and other fatal police shootings in Missouri and elsewhere that activists say are racially motivated.

Organizers of the four-day Ferguson October events expected 6,000 participants, but the initial protest Friday outside the St. Louis County prosecutor's office in Clayton didn't draw nearly that amount. Later Friday, tensions increased, with protesters outside the Ferguson Police Department chanting anti-police remarks such as, "Killer cops, KKK, how many kids did you kill today?" as a wall of 50 officers in riot gear stood near them. The St. Louis County Police Department announced that it would arrest anyone who touched an officer.

Protesters renewed their call for prosecutor Bob McCulloch to charge Darren Wilson, a white Ferguson officer, in the Aug. 9 death of 18-year-old Brown, who was black and unarmed. A grand jury is reviewing the case, and the U.S. Justice Department has opened a civil rights investigation into Brown's death and a broader inquiry into the Ferguson police force.

"We are here to demand the justice that our people have died for," chanted protest organizer Montague Simmons of the local group Organization for Black Struggle. "We are here to bring peace, to bring restoration, to lift our banners in the name of those who've been sacrificed."

Police in Clayton reported no arrests, and officers escorted the several hundred demonstrators through the suburb's downtown as they marched past high-end restaurants, jewelry stores, banks and law offices. Meanwhile, the St. Louis Police Department said it had encrypted its radio communications system because tactical information relayed to officers had been compromised during recent situations, putting officer and the public at risk.

Tensions remain high in the wake of another black 18-year-old's shooting death by a white police officer Wednesday night in St. Louis. Police say Vonderrit D. Myers shot at the St. Louis officer, who was in uniform but working off-duty for a private neighborhood security patrol. Myers' parents say he was unarmed.

The officer's name hasn't been released.

"It's important for this country to stand with this community," said protester Ellen Davidson of New York City, who was making her second trip to the St. Louis area since Brown's death. "This community is under siege. ... The eyes of the world are watching."

On Saturday, the protests shift to downtown St. Louis, hours before the Cardinals host the San Francisco Giants in the first game of the National League Championship Series. And on Monday, a series of planned -- but unannounced -- acts of civil disobedience are to take place throughout the St. Louis region.

"I'm not planning to get arrested," said Davidson, who was meeting up with other protesters from Illinois, Minnesota, New York and Tennessee. "But I do plan to do what I believe are in my rights as a protester. If I get arrested, that's on the people who arrest me."

Brown's parents, the local chapter of the NAACP and other organizations called for peaceful protests ahead of the demonstrations.

St. Louis police arrested eight people Thursday as hundreds gathered to protest Myers' death. At one point officers used pepper spray to force protesters back. A police spokeswoman said one officer was struck in the arm after someone threw a brick, and several cars were damaged.

Black leaders in St. Louis want the Justice Department to investigate Myers' shooting as well. Police said the officer fired 17 rounds after Myers shot at him. Preliminary autopsy results show a shot to the head killed Myers. The officer wasn't injured.

Online court documents show Myers was free on bond when he was killed. He had been charged with the unlawful use of a weapon and resisting arrest in June.