In a tweet, the prime minister said: "The attack in Nigeria is cowardly and utterly condemnable. Condolences to the kin of the deceased. My prayers with the injured."
The attack in Nigeria is cowardly & utterly condemnable. Condolences to the kin of the deceased. My prayers with the injured.— Narendra Modi (@narendramodi) November 10, 2014
A suicide bomber dressed in school uniform was carrying explosives in a rusk sack. The explosion killed at least 48 people at the Government Technical Science College, a boy's high school in northeastern Nigeria.
The militant group Boko Haram is believed to have carried out the attack, police said.
An estimated 2,000 students had gathered in the school's hall at the time of the blast in Potiskum, capital of the Yobe state.
Boko Haram has been targeting school students of late. Earlier they had abducted close to 200 school girls in Nigeria, whom they claim have been converted to Islam and been married off.