Several dozen children staged a "die-in" Saturday morning in Philadelphia, lying down at the intersection of City Avenue and Monument Road to have their young voices heard.

"Everybody is a part of the world, and everybody should be treated equally," said Aniyah Ayres, the eight-year-old force behind the Aniyah's Mission group that helped organize the demonstration.

The children and parents marched carrying signs and chanting phrases that have become recognizable around the country: "All lives matter," "I can't breathe," "No justice, no peace."

The demonstration was one in a series of protests sparked by the high-profile killings of unarmed black men, many at the hands of police. Teenager Michael Brown was killed by a white police officer, Darren Wilson, in Ferguson, Mo.; a grand jury did not indict in that case. In New York, a grand jury also did not indict an officer, Daniel Pantoleo, who was shown on video using a chokehold on Eric Garner, whose last words were "I can't breathe."

Dozens of people joined in one protest early Saturday evening at the King of Prussia Mall. Flooding into gathering areas, including the food court and fountain, demonstrators echoed the chants of weeks of protests.

Before the children marched, a police officer drove up in an SUV. Without fanfare, and just a quick sentence about giving it to the kids, he dropped off a full plate of cookies and then drove off again.

The children left from the Target shopping center parking lot on Monument Road and marched to the City Avenue intersection, around which police officers had rerouted traffic.

The Rev. Charles McNeil Sr., pastor of Transfiguration Baptist Church in Mantua, led the crowd in an opening prayer:

"We are sorry we have to be here, Lord, but we are going to shout until we are heard: All lives matter!" he said.

Demonstrators then bowed their heads for four minutes of silence — one minute for each hour that Michael Brown's body lay in the street after the unarmed black teenager was shot and killed by Wilson.

Children took to the ground, simulating death as their parents stood in a ring around them, their hands raised in the "hands up, don't shoot" gesture that has become a symbol of the protests.

One at a time, four young demonstrators stood up to represent a recent death that has galvanized demonstrators: "I am Trayvon Martin … Tamir Rice … Eric Garner … Michael Brown."

Their parents began to chant: "Those are our children, and their lives matter!"

Parents said they worry about their kids and the racial injustices they may face, from a young age and in particular when they grow older into teenage and young adulthod.

"When I grow up, I want to have a happy life so I don't die," said Raheem Vaughn, 7.

Vaughn's mother said she brought Raheem and his nine-year-old brother, Rasheed, to help them be aware of their voices.

"I wanted them to understand the importance of justice in the community, I want them to understand that their lives matter. I want them to understand that it's time for them to stand up for what's right," said Neshea Jackson, 47, the boys' mother. "I wanted to bring them out to show them that."

Jackson said she was frustrated by a seeming lack of progress over racial issues — "after years and years of this stuff happening … I thought we would be past this injustice" — but that the recent waves of protests were a heartening sign of change.

McNeil, who delivered the opening prayer, echoed Jackson's frustration over lack of change. He agreed that the children in Saturday's demonstration could themselves experience unfairness that would lead them to call for change.

"It's unfortunate that we're still here after so many years, and fighting seemingly the same fights we fought back in the '60s. And at some point, hopefully America realizes that our children matter just as much as children of white parents," McNeil said.

"Children are children, but they're not blind. … And unfortunately, they grow up knowing that there's something different between them and somebody else, by the way that they're treated," he said.

Aniyah's mother, Angelia Gibson-Ayres, said she decided to put Saturday's demonstration together because her daughter kept seeing news coverage of protests and wanted to join.

Gibson-Ayres said the rally was not meant to oppose police, but teach children about ongoing social issues.

"We're not anti-police … I'm still teaching her that police are our friends," Gibson-Ayres said. "Now, sometimes, they do make mistakes, so I'm teaching her that when a mistake was made, it's how you correct that mistake that makes all the difference in the world."

Aniyah's father died when she was two; she chose to take up his causes of promoting education and helping the less fortunate, her mom said. As the head of her Aniyah's Mission organization, Aniyah's fundraisers and donation campaigns have included donating book bags to low-income children and giving out winter coats during Thanksgiving and Christmas.

In a closing prayer, Stanley E. Stocker III said communities must continue to demand change.

"We bless you, Lord, for this die-in. Unfortunately, it was necessary because of the dying. In our city, our children have been shot down by the very ones who are supposed to protect, Lord."

"We don't have to trust in the government, this is not a job for the government. This is not a job for the president, this is not a job for the mayor, this is a job for your people," Stocker, servant leader at Mount Airy Church of God in Christ, said in his prayer. "This is not a job for Superman, but this is a job for your people."