Kuldip Singh of Nangal Maroof and Harpal Singh of Hussainpur Guru Ka were studying in the same class and there was old enmity between them on some issue, police said.
Harpal Singh today attacked Kuldip and stabbed him with a knife, they said.
Kuldip was first admitted to Civil Hospital, Hoshiarpur from where he was referred to DMC, Ludhiana after his condition deteriorated.