It was not immediately clear if Islamist militants were behind the explosion. Bombings and attacks by armed insurgents now happen almost daily in Nigeria’s north, where militant group Boko Haram is trying to carve out an Islamist state.
The blast at the Kano State School of Hygiene tore through an area just inside the college’s main gate, a popular spot where students often gather at food kiosks between classes.
Police took one suspect in for questioning, state Police Commissioner Adenrele Shinaba told reporters. The blast was so severe that several cars parked nearby were badly damaged, he said.
Witnesses said the blast caused people working in central Kano to flee the city center.
Boko Haram gained global attention in April when it abducted more than 200 girls from a rural school in northeast Nigeria.
Kano, the north’s largest city, was hit by unrest earlier this month when hundreds of youths took to the streets against a decision to appoint Nigeria’s former central bank governor as the country’s second-highest Islamic authority.
Last month, a suicide car bomber killed five people on a Kano street lined with popular bars and restaurants, in an area mostly inhabited by southern Christians.
Amnesty International estimates that more than 1,500 people were killed in northeast Nigeria in the first three months of this year.