o [PHOTOS] Martin Luther King Jr. Parade & Unity Rally in Waikiki

ATLANTA » Speakers honoring the Rev. Martin Luther King Jr. at his spiritual home in Atlanta repeated the same message on his national holiday Monday: We’ve come a long way, but there’s still much to be done to fulfill King’s dream.

The holiday came against the backdrop of recent national protests over the deaths of unarmed black men and youths at the hands of the police around the U.S. Some new protests flared Monday: several dozen demonstrators blocked traffic while marching in Cleveland, Ohio, and protests also were reported in St. Louis, Missouri and Seattle, Washington.

In Atlanta, King’s daughter, the Rev. Bernice King, urged those gathered at Ebenezer Baptist Church for the 47th annual Martin Luther King Jr. Annual Commemorative Service to act out against injustice. She also said they should heed her father’s message of nonviolence.

"We cannot act unless we understand what Dr. King taught us. He taught us that we still have a choice to make: nonviolent coexistence or violent co-annihilation," she said. "I challenge you to work with us as we help this nation choose nonviolence." The courage and sacrifice of the civil rights activists of the 1950s and 1960s provide a model for those seeking to effect change today, she added.

She also made reference to the high-profile deaths. Those have included the deaths of unarmed black men in Ferguson, Missouri, and in New York City, as well as the fatal shooting of a 12-year-old boy in Cleveland, Ohio. All three were killed by white officers.

"I cannot help but remember many women and men who have been gunned down, not by a bad police force but by some bad actors in a police force," she said.

The Northeast Ohio Media Group reported about 60 people gathered Monday at a recreation center where a Cleveland police officer fatally shot the 12-year-old. Their march ended at the city’s public square and police told the group some arrests were made.

In Seattle, authorities reported a handful of arrests after dozens chanting "black lives matter" disrupted traffic in Seattle, blocking part of a state highway and interstate off-ramps. Seattle officials advised motorists to take alternate routes when one side of a key state route was temporarily blocked.

The deaths have sparked a nationwide debate over police use of force, further fueled after two New York City police officers were shot to death last month by a man who suggested in online posts that he was retaliating for deaths in Missouri and New York. The gunman, who was black, committed suicide.

The name of the New York man who died in a white police officer’s chokehold was invoked by some during peaceful tributes in New York.

"We will move forward as a city. We will move forward to deeper respect for all," New York Mayor Bill de Blasio vowed at the city’s main MLK Day event in Brooklyn.

Elsewhere, The St. Louis Post-Dispatch reported that two dozen protesters interrupted a King event at Harris-Stowe State University in that area, leading to angry confrontations with students outside a campus auditorium. Police kept watch, but no arrests were reported.

President Barack Obama, the nation’s first black president, sought to focus on the next generation. In Washington, Obama and his wife Michelle went with one of their daughters, Malia, to a site for the Boys and Girls Clubs of Greater Washington to paint murals and assemble "literacy kits" of flashcards and books to help youngsters improve their reading and writing skills.

In Philadelphia, activists pressed for several social justice causes under the King mantle, saying they wanted better police accountability, more education funding and a higher minimum wage. And in Denver some held signs up about the recent deaths as tens of thousands, including cowboys on horseback, made it one of the biggest turnouts in years for Denver’s event. Drill teams and floats paraded in Las Vegas under the theme: "Living the Dream: Where Do We Go From Here?"

In Atlanta, many reflected both on the present and the past.

A day after he joined other actors from the movie "Selma" and hundreds of others in Alabama for a march to Selma’s Edmund Pettus Bridge — where civil rights protesters were beaten and tear-gassed in 1965 — actor David Oyelowo said during the Atlanta commemoration that playing King was a heavy burden.

He cried as he talked about putting himself in King’s place. "I only stepped into his shoes for a moment, but I asked myself, ‘How did he do it?’" Oyelowo said.

U.S. Rep. John Lewis told the Atlanta crowd he was just 17 when King sent him a bus ticket to head to Alabama to join the civil rights movement. Lewis, who marched alongside King, recalled the man he called his hero a man who is "still a guiding light in my life."

"The memory of such a great man can never, ever fade," Lewis said. "I still think about him almost every day."

Associated Press writers Darlene Superville in Washington and Randall Chase in Wilmington, Delaware, contributed to this report.