A Long Island high 15-year-old was busted for stabbing a classmate in the chest with a 4-inch kitchen knife during a tiff in the high school’s parking lot, officials said.

The unidentified Sachem High School East student attacked the student during a confrontation on Friday afternoon around dismissal time, Sachem Central School District Superintendent Patti Trombetta told The Post.

“As a result, a student was immediately transported to Stony Brook University Hospital,” Trombetta added.

“All our thoughts are with the student and his family at this very difficult time,” Trombetta said.

It was unclear what the victim’s condition was on Sunday. 

Suffolk County cops immediately took the stabber into custody and he was held in local jail pending his next court date, officials said.