A mortally wounded gangbanger hated cops so much, he defiantly refused to identify his killer — instead telling officers, “F–k you, son!” with one of his last breaths, law-enforcement sources told The Post Wednesday.

Arsenio Gravesande’s refusal to aid police came amid five fatal shootings over less than 24 hours in the Big Apple — and underscored the hurdles cops face as they try to keep the city safe amid an uptick in shootings this year

Gravesande, 28, was blasted on the left hip during a beef on a Brownsville street corner at around 9:20 p.m., sending first responders racing to the scene at Union Street and Sutter Avenue, authorities said.

Cops asked Gravesande — a known Crip with 43 arrests on his record, including resisting arrest — his name and who attacked him, but received only the vulgar three-word response.

“F–k you, son!” Gravesande — a pal of reformed Crip and slain rap star Nipsey Hussle — told the officers shortly before he was loaded into the back of an ambulance, according to sources.

Responders didn’t initially believe the injury was life-threatening, and cops planned to speak with him once he was settled at the hospital.

“Sometimes, they cool down and talk to us,” a police source said. “They have a change of heart and ID the shooter.”

But Gravesande knew he was dying and admitted as much not long after being put into the ambulance, his grieving cousin said.

“I went in there [the ambulance] with him,” said Bethany Samuels, 35. “He was just moving, trying to grab this, grab that. It’s like his spirit wasn’t at peace. He was saying he couldn’t breathe, [that] he was dead.”

Doctors at Brookdale University Hospital Medical Center determined the bullet had struck multiple arteries, sources said.

Gravesande went in for emergency surgery, but could not be saved — becoming one of five people shot dead across Brooklyn and Queens in the span of 22 hours on Tuesday.

The bloodletting began at around 12:30 a.m. in Springfield Gardens, Queens, when Angel Nixon, 18, was riddled with bullets to his head, torso and legs during what sources said was an argument over a loud party.

Later, at around 8:10 p.m., Gregory Haskins, 25, was found with a fatal gunshot wound to his chest on Sutphin Boulevard in Jamaica, Queens.

And less than an hour after Gravesande was killed, two more men were gunned down in Coney Island. One victim, 38, caught a bullet in the head, while another, 27, was struck in the stomach in a scrap outside a home on West 19th Street, authorities said.

Their names were being withheld pending family notification, but sources said that both men had double-digit arrest totals and were believed to be gang-affiliated.

As of late Wednesday, no arrests had been made in any of the five slayings, which came amid a troubling rise in gun violence across the city.

Shooting incidents this year are up 4.2 percent through Aug. 18 compared with the same period last year, according to the latest NYPD stats, which don’t factor in Tuesday’s outburst.

Some of the murders came in areas particularly dogged by surging gunplay. In NYPD’s Brooklyn North area, which includes Brownsville, stats show a 13.2 percent jump in murders and an 8.1 percent leap in shooting incidents.

And Coney Island’s 60th Precinct has now tallied five murders in 2019 after going all of 2018 without one.