Some protesters attempted to block a door to the police headquarters and faced off with law enforcement officers wearing riot gear. Amid the tense standoff, some protesters sang the song "We Shall Overcome," an anthem of the civil rights movement of half a century ago.
Police arrested a handful of protesters outside the police headquarters including activist, author and academic Cornel West.
Protesters have numbered in the thousands at some events since Friday in the St. Louis area in demonstrations aimed at drawing attention to what they say is police mistreatment of blacks.
Chanting "black lives matter" and other slogans, protesters joined in prayer at a local church before marching to the nearby police department, a target for many who have expressed outrage over the August 9 killing of Michael Brown, 18, by Ferguson police officer Darren Wilson.
A grand jury is considering charges against Wilson, who has been placed on administrative leave. Protesters want Wilson arrested immediately and have called for the appointment of a special prosecutor. The US Justice Department has launched a civil rights investigation into Brown's death.
Activists have traveled from across the United States to join in four days of protests dubbed "Ferguson October," culminating on what organizers call "Moral Monday" with activities protesters said likely would result in many arrests.
"The weekend has been incredible to help re-energize those of us that are here," said Ferguson Democratic Committeewoman Patricia Bynes.
"People are still very much following closely what is going on," she said. "The message is getting out there."
Several local and national religious leaders have been taking part in the protests, and have said they hope to build momentum for a nationwide movement against police violence.
"The faith community is standing shoulder to shoulder with the people of Ferguson in one of the defining civil rights moments of our generation," Reverend Deth Im, a member of the PICO National Network group of faith-based community organizations, said in a statement issued Monday.
There have been numerous protests in the two months since Brown was killed. Tensions escalated in recent days after a white officer in St. Louis shot and killed another 18-year-old black man, Vonderrit Myers Jr., on October 8.
The events in Ferguson have focused global attention on the state of race relations in the United States and evoked memories of other racially charged cases, including the fatal shooting of black teenager Trayvon Martin in Florida in 2012.
More than 1000 protesters shouted slogans at police on Sunday night into the pre-dawn hours on Monday in St. Louis, near where the white off-duty officer shot and killed Myers last week. Police said Myers had opened fire, but his family maintained he was unarmed.
