NEW YORK, United States -- A 12-year-old boy was shot and killed as he sat in a parked car Thursday night in New York City, police said, shining a light on surging gun violence in the US megacity.

A young woman in the driver's seat was also shot multiple times, while an eight-year-old girl in the back of the vehicle was uninjured, police added.

The three had been waiting for food in the city's Brooklyn neighborhood when gunfire was reported at about 8pm, police inspector Michael Kemper told a late-night press briefing.

"In the passenger seat, there was a 12-year-old boy who had been shot multiple times. He died on the spot," Kemper said.

The driver, 20, was "expected to survive" after being taken to hospital for surgery, he added.

Police did not say whether the victims had been targeted or hit by stray bullets.

Crime in the city of nearly nine million has risen sharply since 2020, according to official statistics, particularly acts involving firearm violence.

New York Mayor Eric Adams, a former police officer who was elected in January on a platform of tackling crime including the illegal spread of guns, expressed dismay while speaking to reporters Thursday night.

"What about the innocent people? What about people that are sitting in their cars and are shot and killed?" he asked.

"When are we going to start fighting for the innocent people of this city?"

"As long as we have guns and a revolving door (prisons) system, we will continue to have crime scenes like this," he added.

In January, Adams called on the federal government to help "stop the flow of weapons" in the city after a police officer was killed and another wounded in a shooting.

Last month, police turned to the public for help identifying a man who shot at least two homeless people, killing one of them as he slept on the street.