The circle of people was thin but spread wide, looping an intersection in the heart of Harlem on Sunday and blocking long lines of cars and buses in four directions. In the middle of the circle stood a cluster of angry people, and in that cluster stood a young man with a bullhorn and a question.

“Why isn’t everyone else out here with us?” the man, Robert Cuffy, 22, asked. The circle of people, roughly 150 strong, stared back. It was two days after a judge acquitted three New York City detectives in the shooting death of Sean Bell, who died on the morning of his wedding day 17 months ago after the detectives fired a total of 50 bullets at his car.

Unlike some previous verdicts in police shootings, the acquittals in the Bell case have so far been largely met with a muted response. Thousands of protesters did not fill the streets, no unrest ensued. Still, on Sunday, some protesters and advocates around the city demanded federal investigations into the case and greater oversight of the police, while others puzzled over why the verdict had not yielded a stronger response.

At a news conference at the Harlem headquarters of the Rev. Al Sharpton’s National Action Network, Mr. Sharpton and other activists, politicians and community leaders praised the overall peaceful response that followed the verdict, and vowed to fight the judge’s decision in strategic rather than bellicose ways.

“Some in the media seemed disappointed, they wanted us to play into the hoodlum, thug stereotypes,” Mr. Sharpton said. “We can be angry without being mad.” And while many onlookers shouted their support, others admitted restlessness and a yearning for something more.

“People are hungry for leadership that’s not there,” said Calvin B. Hunt Jr., who listened to the news conference and joined the protest that followed, marching down Malcolm XBoulevard and blocking the intersection at 125th Street. He spoke longingly of prominent black activists in the 1960s and 1970s, among them Malcolm X, Angela Davis and Huey Newton. “After the Amadou Diallo verdict, we marched till we had corns on our feet, and nothing changed,” he said. “In this verdict, there was no justice. So why should there be peace?”

His sentiments were shared by some others in the crowd. A poet who gave his name as Thug Love said gang members from the Bloods and Crips should unite to “police and protect their own community” the way the Black Panthers did decades ago. A concert promoter, who goes by the name Goddess Isis, said that the news conference sounded to her like “politics as usual,” and that the community needed grass-roots leaders with concrete solutions to ongoing problems, like police harassment.

“We are on our own here,” she said.

But Nkrumah Pierre, a banker who lives on Long Island and who marched in the protest on Sunday, said: “We’ve progressed to the point where we don’t need to act out in violence. This is an intelligent protest, and a strategic protest.”

Still, others on Sunday called for changes within the system, in particular the ways in which the city’s police are monitored.

At a news conference outside Police Department headquarters in Lower Manhattan, civil rights advocates and lawmakers — including Norman Siegel, the former executive director of the New York Civil Liberties Union; State Senator Eric Adams of Brooklyn; and Marq Claxton of 100 Blacks in Law Enforcement Who Care — called for the appointment of a permanent statewide special prosecutor, to supersede district attorneys in cases of police shootings or alleged police brutality.

Too often, the advocates said, district attorneys have close relationships with the police, muddying prosecutorial independence. The advocates also said the timing of the proposal was influenced by the ascension of David A. Paterson to governor.

“For the first time we realistically have someone in the governor’s seat that understands the need for these reforms,” Mr. Siegel said.

The proposal, Mr. Siegel said, was loosely patterned on the former Office of the Special State Prosecutor for Corruption, created under Gov. Nelson A. Rockefeller in the early 1970s on the recommendation of the Knapp Commission, which uncovered corruption in the Police Department. That office was disbanded in 1990.

Risa Heller, a spokeswoman for Mr. Paterson, said the governor would review the recommendation. “Like all New Yorkers, the governor takes the issue of police wrongdoing very seriously, but he also believes that the overwhelming majority of police officers perform their duties honorably and conscientiously,” Ms. Heller said.

In Harlem, one of the protesters, Melanie Brown, who is 29 and lives near the street in Queens where Mr. Bell was killed and two of his friends, Joseph Guzman and Trent Benefield, were wounded, said she believed that every response, no matter how seemingly small, helped.

“What happens next happens,” she said, as protesters chanted and hoisted aloft Pan-African flags, striped in red, black and green. “Right now this is a unity thing.”