A man allegedly shot and killed his sister’s boyfriend in Brooklyn on Friday, sources said.

The suspect shot his 23-year-old rival in the stomach and arm when he opened fire in East Flatbush at about 5 p.m., according to police sources.

An unidentified driver took the victim to Brookdale Hospital, where he died.

The boyfriend’s identity was being withheld, pending family notification.

The suspect fled after the attack. Cops were searching for him Friday night.