The sister of a Bronx teenager who police say died while subway surfing said her brother, who she described as “shy and quiet,” was hanging out with “the wrong crowd” before the fatal incident on July 4.

“He started acting more like a teen, common teenager behavior, hanging out with different groups that didn’t seem to want the best for him, wouldn’t help him in school, wouldn’t help him,” said Emely Oliver. “I feel like friends are supposed to be there for each other.”

News 12 was told first responders found 15-year-old Carlos Oliver unresponsive atop a No. 7 subway car inside the Queensboro Plaza subway station.

Police said it happened around 2:45 a.m.

News 12 asked the teen’s sister why her brother wasn’t home at the time.

“We told him to be home by 8 p.m., and around 7:30 a.m. we [asked] him, ‘Where are you? Are you coming home?’ And he asked to sleep over at a friend’s house, and we told him no.”

Emely said that was the last time she heard from her brother.

Oliver was taken to a hospital where he was pronounced dead. Police told News 12 the teen was with three other kids who ran off before first responders arrived.

Oliver’s parents were too distraught to speak to News 12 on Saturday, but the family said they’re sharing their story in hopes that it stops someone else from subway surfing and prevents another family from feeling their pain.

"They think it’s so amazing, it’s so cool,” Emely said. “For what? You’re going to hurt yourself. You’re going to hurt others, and it’s not worth it.”

As of Saturday, police said no arrests have been made.