A Milford Mill Academy while walking toward Rockdale Terrace was also robbed, police said.
Some media reports question whether the student was somehow involved in the robbery. But, according to a Baltimore County Police report, the student was the victim.
At about 11:55 a.m. Monday, two males approached the 17-year-old boy behind the school at 3800 Washington Ave., and demanded his cell phone, the report states.
"The victim placed the suspect in a headlock. After a short struggle the suspect stabbed the victim in his right thigh," it states.
He was taken to a local hospital.
A school official told WBAL Radio on Monday that the victim had left the school without permission, according to a WBAL Radio report.