By CLAUDIA LAUER
Associated Press

PHILADELPHIA (AP) - Two gunmen firing from opposite sides of a Philadelphia street unleashed a hail of bullets on four children, killing a 14-year-old boy, police said.

Authorities said at a news conference Tuesday that the other three children were wounded, including an 11-year-old boy, and were in stable condition. A 24-year-old man who was walking a short distance away was also shot in the abdomen, but police said the teens were the intended targets.

The victims were outside on a sidewalk at about midnight Monday when the shooting occurred in North Philadelphia. Capt. John Ryan said at least 21 shots were fired, all from the two gunmen who acted in concert. He said the victims, who all live within a block of the shooting site, did not return fire.

Police did not release the name of the 14-year-old who was shot in the forehead and died from his injuries hours later.

"As far as a motive for this, we don't know yet. It's probably some kind of neighborhood dispute, as is often the case with kids this age," Ryan said.

He said the victims are cooperating. Ryan said investigators are reviewing surveillance footage and a $20,000 reward has been offered for information leading to an arrest.

Ryan said they don't have any suspects, and that the shooters were wearing dark clothing and hoodies.

"It's clearly an issue in the state of Pennsylvania, the city of Philadelphia ... with the availability of handguns when kids this young can be involved in something like this," Ryan said.

He said there is a summer curfew in the city of Philadelphia, which the children were violating.

Former Mayor Michael Nutter signed a curfew into place in 2015 requiring children under 13 to be inside by 9 p.m., minors 14 to 15 by 10 p.m., and minors 16 and older by 11 p.m. during the summer.