Staring into the clear, cold sky Sunday night, Danielle Duncan joined a group of about 30 who lay silent on the street in front of the Philadelphia Museum of Art, surrounded by hundreds of fellow demonstrators.

"I'm kind of flustered," Duncan, 21, said after standing up, her voice catching with emotion. "I feel like we're just not seeing equally. I don't feel like it's the fault of anyone, but we have to adjust to it."

Duncan was one of almost 1,000 people who marched from LOVE Park to the museum in yet another protest over what they perceive to be police brutality and racial tension across the country. A large contingent of police kept pace with the crowd organized by BlackOut Philly, but there were no signs of confrontations, and police said there were no arrests in the first hours of the protest.

Later in the evening, however, the protesters split into several groups that continued their march in different parts of Center City, with some attempting to move to the Vine Street Expressway.

Organizers said they were concerned about killings of unarmed black men by white police officers, including Michael Brown in Ferguson, Mo., and Eric Garner, who died in a choke hold in an altercation in Staten Island, N.Y.

Grand juries in both states declined to indict any officers involved, sparking protests and "die-ins" around the country.

Sunday's event was one of many since those grand jury decisions, but it was the first since two New York City police officers, Wenjian Liu, 32, and Rafael Ramos, 40, were killed Saturday by a black man with a criminal record who said he was motivated to commit violence by the Brown and Garner decisions.

Most people participating Sunday sought to distance their event from the murders in New York.

"I care about black people," said Denise Howell, 25, a Temple University student. "I care about our entire country. I don't want to see us go to civil war over race."

Mayor Nutter commented on the killings in New York in a statement Sunday. "This cruel and irrational act was perpetrated by a person who wanted to make a statement about police-community relations," Nutter said. "Instead, he underlined the evil of violence."

Several observers not participating in the protest showed support for the city's officers.

One woman shouted, "Thank you for all that you do," from her car as she drove by a line of bicycle officers.

Another woman observed a group of officers on bicycles clearing the street ahead of the demonstration and asked whether participants were protesting the police who were clearing the way for them?

The march began at 15th and Arch Streets with participants chanting, "I can't breathe," and "Hands up. Don't shoot."

Though event organizers initially said the demonstration would wind around City Hall and go to LOVE Park, plans seemed to change en route, and the crowd moved up the Ben Franklin Parkway to the Art Museum.

There was Tonya Dickerson, mother of Brandon Tate-Brown, the 26-year-old ex-convict killed by police last Monday during a traffic stop in Mayfair.

"This cannot keep happening," Dickerson said as protesters held up their cellphones to illuminate the museum steps, and others lay down in a show of solidarity with Michael Brown.

Word of the BlackOut Philly march spread largely through social media.

Before the march, organizer Raheem Harvey, 25, of West Philadelphia, and a few others met at the AT&T Station on the Broad Street Line.

"This is not a demonstration to be against police, but against police brutality," Harvey said on camera for fellow activist Alicia Dorsey, 45, who said she was making a documentary.

Two white college students carrying signs reading, "White silence = white acceptance" and "Respect existence or expect resistance," said they were there to show solidarity with blacks who were "systematically imprisoned and killed in this country."

They did not want to give their names because, they said, the African American protesters "are the ones whose voices need to be heard."

Alfred Watts, 25, a Delaware County corrections officer, said he had been talking to police officers in other cities to see what kinds of police feedback or public forums they have.

"In Philadelphia, we have no programs in place," he said. "Police officers do whatever they want and get away with it."

Hours later, outside the Art Museum, Duncan emphasized that she wasn't angry at police.

"I don't have anyone to be angry at," she said, preparing to march back toward City Hall. "I just want for change, and I'm disappointed with the way things are now."