Tens of thousands of protesters poured through the streets of Manhattan on Saturday in New York City's largest demonstration since a grand jury decided not to indict an NYPD officer in the death of Staten Island resident Eric Garner.

The "Millions March NYC" procession stretched for about a mile as protesters shouting "I can't breathe" wound from Greenwich Village to midtown and then to downtown police headquarters.

The 4-hour march was more orderly than related protests in the city over the last 10 days. At 8 p.m., about two hours after the demonstration officially ended, no arrests or criminal incidents had been reported, said Det. Brian Sessa, an NYPD spokesman.

After organizers announced the end of the rally about 6 p.m., groups of protesters continued to move through Manhattan and Brooklyn, at one point shutting down the Brooklyn Bridge.

The crowd numbered about 25,000, according to a police source. There were double that figure, according to march organizers.

Participants, holding signs and joining in chants, said the criminal justice system does not hold white police officers accountable for using unnecessary force on black men.

"We have to speak out against violence," said Tolulope Oyetunde, 24, a medical student at Rutgers University. "We have to respond and stand up," she said.

Turquoise Young, lawyer and march organizer, said the group's most pressing demand is the firing of NYPD Officer Daniel Pantaleo, who was seen on video using an apparent chokehold on Garner, 43, on July 17.

"He violated NYPD policy not to use a chokehold," said Young, 30, of Harlem. "There should be accountability."

Family members of men killed by police led the march, holding a banner proclaiming "Black Lives Matter."

They walked four miles before rallying outside NYPD headquarters.

"I had to come home because there's a change happening and I feel that I need to be here," said Iris Baez, whose son Anthony Baez died after a 1994 scuffle with police in the Bronx. She said she flew from Florida to join recent protests in New York City.

Eric Cavallari, 34, of Shirley who joined the protest, said the NYPD "isn't a bad institution" but needs "reforms."

"Let's make this institution of the NYPD better, get the racist and killer cops out," he said. "This isn't the Deep South. This isn't Mississippi in the 1960s. This is New York City in 2014."

The rally outside 1 Police Plaza dispersed around 7 p.m., but protests continued, at one point blocking the Brooklyn Bridge.

It was the latest demonstration to follow the deaths of Garner, 43; Michael Brown, 18, shot dead by police Aug. 9 during a street confrontation in Ferguson, Missouri; and Tamir Rice, a 12-year-old carrying a BB gun shot dead Nov. 22 by an officer in Cleveland.

A Staten Island grand jury voted Dec. 3 not to indict Pantaleo in Garner's death, setting off daily demonstrations on the streets of New York City.

Earlier Saturday, NYPD PBA president Patrick Lynch, speaking at an event for the families of fallen police officers, stood by his call for officers to request that Mayor Bill de Blasio and City Council Speaker Melissa Mark-Viverito stay away from funerals of officers killed in the line of duty.

Lynch has decried the city officials' calls for change in the NYPD after the Garner case.