Tensions rose as at least 3,000 protesters converged in Times Square about an hour before midnight. Blocking the major interaction of 42nd Street and Seventh Avenue, they chanted at police, "Who do you protect?" Soon hundreds of officers shoved them onto sidewalks.

Earlier, protesters in lower Manhattan staged sporadic sit-ins at intersections before police in riot gear warned them to move on or face arrest. Most complied.

Sharon Gordon, 52, of Matawan, New Jersey, said she hoped politicians would take heed. “There’s been a confluence of social media and outrage,” she said. “I do believe, for the first time, we’re about to make a change.”

Waves of marchers also blocked traffic on two bridges between Manhattan and Brooklyn, then converged on the Staten Island Ferry terminal at Manhattan’s southern tip. The main group headed west and temporarily shut the West Side Highway, resulting in at least a handful of arrests, before turning north toward Times Square.

Although the marches disrupted traffic, many motorists, bus operators and taxi drivers expressed their support of the protest with high-fives, honks or the hands-up gesture that has become a familiar rallying symbol for protesters.

A few protesters could be heard taunting black police officers with shouts of “traitor.”

Others bemoaned a series of arrests in midtown Manhattan at about 12:30 a.m. Friday morning. “They shoved this kid’s head right on the ground,” said Adam Raleigh, 24, who said he wasn’t sure what caused a commotion that ended in at least seven arrests there.

Daniel Dealada, 24, a martial arts instructor from Harlem who is black, said that the events of the last two months have made him aware of the effect his skin color might have on the way authorities treat him. His mother, who grew up in the apartheid era of South Africa, always taught him to be “very aware that I am a black man,” he said.

“It makes her sad that she has to fear for my life,” Dealada said.