The stray bullet reportedly came from a shooting in the nearby Morro do Borel slug, in the north of the city. The bullet hit Alvares in the torso while he was waiting for the bus that would take him to school.

The military police said in a statement that members of a local police unit were shot at by criminals but the officers did not shoot back. Some residents, however, told The Associated Press there was an exchange of gunfire between criminals and the police.

Dozens of angry residents of Morro do Borel blocked the road where Alves died.

"This has to stop!" shouted Jaiane Cristina, a cousin of Alves' mother who was standing a few meters (yards) from where he was shot. Some held signs saying "Another innocent death."

Alves is one of 110 people hit by stray bullets in the Rio metropolitan area so far this year, according to data from Fogo Cruzado, a group that monitors shootings in the area. Thirty-one of those people have died, it said.

In the first six months of the year, Fogo Cruzado recorded 4,169 shootings, or about 23 a day.

"I imagine going to work and receiving a phone call telling me my son was found dead on the street. I don't want this for my son, I don't want this for anyone," Cristina yelled.

Tensions eventually rose between the protesters and police officers, who used tear gas to disperse the small crowd.

President Jair Bolsonaro, a far-right former army captain, was elected last year on a promise to tackle epidemic violence in Brazil and to crack down on criminals.