Baku, April 15, AZERTAC

At least a dozen people were arrested on Tuesday when demonstrators angered by fresh cases of U.S. police violence against unarmed black men marched across New York's Brooklyn Bridge, hoping to invigorate a national discussion on the issue.

Some 250 placard-bearing activists organized by the Stop Mass Incarceration Network marched from Union Square to protest the latest incidents of violent police tactics used against minorities.

"Stop murder by police" and "Stop killer cops," the signs read, as a helicopter hovered over protesters facing off against police officers.

At least 12 people, some of whom appeared to be school-aged, were arrested following a brief scuffle with police after they crossed the bridge.

"She has homework to do," a teen who declined to give her name shouted at police as one of the people was marched onto a New York Police Department bus.

Galvanizing their cause was the April 4 fatal shooting of Walter Scott, an unarmed black man shot in the back by a white police officer in North Charleston, South Carolina.

The shooting was captured on video, and the officer has been charged with murder.

Family members of several unarmed black or Hispanic men or boys who died in encounters with police called for more oversight.

"What this protest right here is about is that too many are being murdered," said Nicholas Heyward Sr., whose son Nicholas Heyward Jr. was shot dead at age 13 in public housing by a police officer 20 years ago while playing cops and robbers with a toy gun.

"I have been fighting for the last 20 years to get that case reopened," he said.

"It's painful because not only do I have to wait but while I'm waiting, I am constantly seeing innocent victims gunned down on the street for no reason at all."

Last year, a tide of protests was inspired by a string of high-profile cases of black men losing their lives at the hands of white police officers.

But the manifestations of indignation following the deaths of Michael Brown in Ferguson, Missouri, and Eric Garner in New York slowed to a standstill over the winter.

Another group of protesters, led by Justice League NYC, has embarked on a 250-mile trek to Washington from New York City to demonstrate against police-related deaths.

They are due to reach the National Mall on April 21.