Multiple shootings shake Detroit, Phila.

DETROIT — A shootout at a block party in Detroit left a 19-year-old gunman dead and 11 other people wounded, police said, while 10 people were injured, including a toddler, at a Philadelphia cookout when they were hit by birdshot from a shotgun, and two men are being sought.

The two multiple-shooting incidents come just three days after a gunman massacred nine church members in Charleston, S.C., in a bloodbath that has brought focus back onto the pervasive and divisive issue of gun crime in the United States.

Standing on basketball courts where the shooting happened about 8:30 p.m. Saturday, police Chief James Craig said officers are seeking two men believed to have exchanged gunfire with the victim, Malik Jones, amid 300 people barbecuing and celebrating. So far, he said, witnesses and the injured haven’t been much help.

“This is a passionate plea for the neighborhood to say something and step up,” Craig said, standing a few feet from a small child’s chair and a table. “These are urban terrorists … We are fortunate we don’t have any young children recovering from a gunshot wound.”

Residents have been reluctant to cooperate with police, the chief acknowledged, with witnesses apparently concerned that they may put themselves at risk.

According to the chief, the 19-year-old had been shot and wounded recently and Saturday’s exchange of gunfire was believed to be in retaliation.

The double basketball court is run by the adjoining Dexter-Elmhurst Community Center, said Helen Moore, chairwoman of the private group that manages the center.

“It’s a good community,” Ms. Moore said. “I know there are people in the community that know what happened and are afraid to speak up.”

“I’m not afraid of anything but God,” she added.

In Philadelphia, witnesses told police that the suspects fired down a block with a shotgun at least once in West Philadelphia’s Belmont neighborhood shortly before 10 p.m. Saturday. Police said the pair then drove down the street in a gold sedan, firing several more shots, possibly with a handgun.

“It looks like they just randomly fired down the street and just hit whoever was in their way, which is just a terrible situation,” Philadelphia police Lt. John Walker told reporters at the scene.

Shortly before the shooting, a man was found less than a mile away with multiple gunshot wounds. He was pronounced dead minutes later at a local hospital. Police said there was no indication whether that shooting is connected to the later gunfire.