At first, the dancers were joyful, leaping in circles and wrapping in a bear hug the young man portraying slain 12-year-old Tamir Rice, who was shot to death by Cleveland police at a playground in November 2014.

But then the drumbeat turned staccato, his body jerked, and the other dancers rushed him in attack. He fell dead, his white shirt now smeared with black paint to symbolize bullets.

Tamir Rice’s death unfolded Saturday afternoon in an interpretive dance by Black Lives Matter protesters inside the North Station concourse at the entrance to TD Garden, as Celtics fans streamed past. About 150 protesters had traveled from Park Street Station to the Garden, where the Celtics were playing, to protest last month’s grand jury decision to not indict the police officer who shot Rice. The boy was holding a replica gun at the time.

“We’re gathered here in TD Garden, a landmark of joy and play,’’ shouted organizer Daunasia Yancey. “But our children can’t play in peace. So they don’t get no peace! Right?’’

The crowd roared back, “Right!’’ and a chant began:

“No justice, no peace!’’

The protest began around 12:30 p.m. at Park Street, as marchers gathered and three people on drums led the swelling group in singing “This little light of mine,’’ and “Buffalo Soldier.’’

“We are out here because the white supremacist violent state keeps taking our people,’’ Yancey told the crowd. “It’s a new year, and we’re not taking it anymore!’’

People carried homemade signs, reading “Black Lives Matter,’’ “#IndictAmerica,’’ and “A society that will not protect its children is doomed.’’

Incense burned, and the protesters shouted out: “Say his name, Tamir Rice, we celebrate his life.’’ The dancers performed for the first time at Park Street, and a Roxbury hip-hop artist who gave her stage name as “Oomp’’ performed an original song that began, “Does anybody know how much a heavy heart holds?’’

Within an hour, the protesters took to the Green Line, crowding onto a train where they chanted, “Indict, convict, send those killer cops to jail! The whole damn system is guilty as hell!’’

When the marchers got to the Garden, security guards appeared to try to prevent them from entering through North Station, but quickly abandoned the effort as the group rushed inside.

Most people passing through to attend the Celtics game or catch a commuter rail train were surprised, curious, supportive, or indifferent to the protesters, who spent more than an hour chanting, singing, and dancing.

“I like this,’’ said Marquis Johnson, who was on his way home and had stopped for a coffee at McDonald’s when he saw the protest. “I like that everybody is dancing together and trying to love each other and work together.’’

Others were more skeptical.

“Cheers,’’ laughed one man there for the game who declined to give his name, tipping his Coca-Cola in the direction of the protesters, when asked what he thought. “I don’t know.’’

“I think it’s interesting they’re only covering black lives,’’ said his girlfriend, who also declined to give her name. “Not anybody else’s life that matters. I’m Hispanic, so.’’

Most of the crowd moved past the protest without comment, though some shook their heads. One man appeared to be shouting something angrily, but a security official moved him along.

Despite the presence of at least 20 security and police officers, there was almost no interaction between protesters and officials.

“We appreciate that they demonstrated peacefully, and we’re always willing to assist these peaceful demonstrations,’’ said Boston police spokeswoman Officer Rachel McGuire. “We thank them for doing so in a respectful manner.’’

The protest ended with a final chant:

“It is our duty to fight for our freedom. It is our duty to win,’’ the marchers shouted in a call and response. “We must love and support one another. We have nothing to lose but our chains!’’

Evan Allen can be reached at evan.allen@globe.com. Follow her on Twitter @evanmallen.