(AP) Hundreds of people rallied and marched in New York and Boston to protest the death of a Baltimore man who was critically injured in police custody as Philadelphia activists prepared for their own demonstration.



More than 100 people were arrested in New York on Wednesday night after police on a loudspeaker warned them they would be taken into custody if they marched in the street.



Police said most arrests were for disorderly conduct. Final figures were expected later on Thursday.



Protesters first rallied in Manhattan's Union Square, where they chanted "No justice, no peace!" and "Hands up, don't shoot!," a reference to the police killing of Michael Brown in Ferguson, Missouri, last year.



Then a group of protesters spilled into the street, disrupting traffic. Dozens of police officers moved in with plastic handcuffs and began making arrests while officers with batons pushed the crowd back onto the sidewalk.



In Boston, activists gathered in a park behind police headquarters in Roxbury and continued with a peaceful march to a park at Dudley Square, across from the Roxbury neighborhood police station.



Nikea Ramsey, whose brother, Burrell Ramsey-White, was shot and killed in an encounter with Boston police in 2012, said, "Me and my family, we stand with Baltimore. We stand with Ferguson. This is too much and it's getting out of hand."



In a statement, Darnell Williams, president and CEO of the Urban League of Eastern Massachusetts, said the civil rights organization "supports those who have chosen to exercise their First Amendment Right to peacefully assemble and let the world know that when we truly recognize that #BlackLivesMatter we take a large step towards ensuring that #AllLivesMatter."



Boston organizers said they want "amnesty" for the some 300 protesters and rioters who have been arrested in Baltimore, as well as a lifting of the city curfew and state of emergency declaration.



In Philadelphia, protesters plan to conduct the "Philly is Baltimore" demonstration Thursday afternoon at City Hall. They've drawn parallels between the death of a local man shot during a traffic stop and the April 19 death of Freddie Gray in Baltimore.



The district attorney is not pressing charges in the December shooting death of Brandon Tate-Brown in Philadelphia, saying evidence indicates that he was reaching into his car for a loaded pistol. A lawsuit filed Tuesday alleges that officers planted the gun.



In New York on Wednesday night, small groups of protesters split off from the main demonstration with one group heading to Times Square, where it held a die-in by lying on the ground. Another group marched to the entrance of the Holland Tunnel as others blocked streets.



Comrade Shahid said he showed up because he believes "the police have become out of control."



"If you kill somebody, it's murder. If the police kill you, it's nothing," Shahid said. "It's making this country's youth anarchists."



Gray's arrest was recorded on cellphone videos by bystanders. His death has led to protests, rioting and looting in Baltimore.



Baltimore police say they chased Gray when he fled at the sight of an officer in a drug-infested neighborhood this month. Officers pinned him to the sidewalk and then lifted him and took him, his legs dragging on the ground, to a police van.



Gray, who asked repeatedly for medical help during the half-hour ride to a police station, died a week later.



Police say Gray died of a "significant spinal injury." An attorney for Gray's family says his spine was "80 percent severed in the neck area."