A 13-year-old boy was stabbed in the back during a brawl in broad daylight outside a school in New York

A 13-year-old boy was stabbed in the back Thursday during a broad daylight brawl with a teenage rival just steps from his school in Brooklyn, sources and police said.

Violence erupted when the two began arguing at Roosevelt Place and Atlantic Avenue in Brownsville, near the Eagle Academy for Young Men in Ocean Hill, around 3:45 p.m., police said.

According to the sources, his 13-year-old attacker then slashed him in the lower back before fleeing the scene.

The victim, who attends Eagle Academy, collapsed on the floor, sources told The Post.

He was taken by paramedics to Brookdale University Hospital, where he was in stable condition.

The teenage stabber had not yet been caught as of Thursday evening.

The investigation is ongoing.