A 15-year-old boy was slashed in the face, possibly with a box cutter, inside his Bronx charter school Thursday — the third burst of Big Apple student violence in as many days, according to cops and police sources.

The unidentified student was rushed to Lincoln Hospital in stable condition following the attack at the AECI Charter School in Melrose, cops said.

Another 15-year-old boy was taken into custody, but no further details are immediately available, police said.

The two students were “fooling around” when one of them pulled out what’s believed to be a box cutter and slashed the other’ face, sources said.

The bloodshed came just the day after a 12-year-old girl was slashed in the leg by a fellow student Wednesday at J.H.S. 123 James. M. Kieran School in the Soundview section of the Bronx.

The suspect in that attack, an eighth-grade girl, 14, and the victim got into a scuffle inside a classroom, possibly related to a social media spat, according to sources.

On Tuesday, a 15-year-old boy at Edward R. Murrow High School in Brooklyn was stabbed after a fight with another teen, according to police.

The student was knifed in the stomach and rushed to Maimonides Medical Center’s children’s hospital, where he is expected to recover, cops said.