The gunman accused of fatally shooting a 21-year-old man in the head as they stepped off a Bronx bus callously continued to shoot his victim as he lay on the ground bleeding to death, prosecutors said as they hit the shooter with murder charges.

The grisly details of the Thursday execution rattled victim Assam Alshaif’s heartbroken family, who don’t know why their beloved relative was targeted.

“We don’t know anything about what happened,” Alshaif’s sister, who wished not to be named, told the Daily News as she wiped tears from her eyes. “We were so shocked.”

Suspected shooter Jadore Reid sprinted off after pumping three shots into Alshaif and ditched his gun, but was quickly caught by police after he ran up to an aboveground subway station at the corner of Jerome and Bainbridge Aves. in the Norwood section of the Bronx.

With the cops hot on his heels, Reid ran back down from the station and tried to get onto another bus before he was taken into custody, police and prosecutors said.

Reid followed Alshaif off the BX16 bus and shot him from behind around 9:45 a.m., cops said.

“(He) followed the victim off a New York City bus, pulled out a gun and shot the victim,” prosecutors said at Reid’s arraignment in Bronx Criminal Court Friday. “The victim fell to the ground and the defendant stood over the victim and fired numerous times, striking the victim in the head.”

Police investigate after a man was shot in the head on Bainbridge Ave. at Jerome Ave. in the Bronx on Thursday, March 26, 2026. (Theodore Parisienne / New York Daily News)Police investigate after a man was shot in the head at Bainbridge and Jerome Aves. in the Bronx on Thursday, March 26, 2026. (Theodore Parisienne / New York Daily News)

The entire incident was caught on area surveillance cameras.

“Police officers were a short distance away and heard the gunshots,” prosecutors said. “They then saw the defendant running with the gun.”

EMS rushed Alshaif to St. Barnabas Hospital, where he died.

Cops charged Reid with murder, manslaughter and weapons possession. Judge Scott Krompinger ordered him held without bail.

The teen’s defense attorney declined to speak to reporters after the brief hearing.

The killing was Reid’s first arrest, an NYPD spokesman said Saturday.

A motive behind the shooting was not immediately disclosed.

Alshaif lives in Wakefield and is the oldest of four siblings, relatives said. He was killed about two miles from his home.

His family overheard him talking to someone on the phone the morning he died. He agreed to meet someone on a bus, which was a departure from his normal routine.

“Before he left, he was on the phone with his friends. He was laughing and he was saying, ‘OK, guys, I’m going to the bus right now,’” his sister, 20, said. “He always takes Ubers, Lyfts. He never takes public transportation, ever. So when we heard (that, we thought), ‘Why was he taking the bus? He never takes the bus at all.’”

“He’s such a sweet guy. He’s a very hardworking person, too,” she said. “He never gets into problems, so that’s why we’re confused.”