Six others were in a serious condition following the attack at Bayero University campus where Christian worshippers were holding a service.
Police are searching for the gunmen.
No group has said it launched the attack, but the violent Islamist Boko Haram group is active in Kano. It has recently attacked churches.
Nigeria’s central government has struggled to contain the militant group, which operates mainly in the predominantly Muslim north, but has also struck as far south as the capital, Abuja.
Sunday’s attack took place in one of the lecture theatres used as a place of worship by Christians.
A witness told AFP news agency the attackers had first thrown in explosives and fired shots, “causing a stampede among worshippers”.
“They now pursued them, shooting them with guns. They also attacked another service at the sporting complex.”
Another witness spoke of “pandemonium”, and said he had seen two men shooting indiscriminately.
Mohammed Suleiman, a history lecturer at the university, said security guards had to run for their lives when the violence broke out.
“For over 30 minutes a series of bomb explosions and gun shots took over the old campus, around the academic blocks,” he told Reuters news agency.
A Red Cross spokesman said adults – possibly professors – and three women were among the casualties. Several needed urgent blood transfusions.
Kano state police spokesman Ibrahim Idris said that by the time police arrived, the attackers had “disappeared into the neighbourhood”. A manhunt is under way.
But the situation at the university was now calm, according to the Red Cross spokesman.
Boko Haram carried out a bombing in Kano in January that killed more than 180 people, its deadliest attack to date.
By Mark Lobel BBC News, Lagos
Police say small explosives inside soft drink cans were used in the attack on the university campus in Kano – trademarks of of the Islamist group of Boko Haram. There are other signs pointing to them – the use of attackers on motorbikes for instance.
The attack – on an apparent Christian service at an education establishment – would match up to threats the group has made in the past. Their name Boko Haram, translated from the local Hausa language, means “Western education is forbidden”. It is a good reflection on the group.
Its purported aim is to destabilise the Nigerian state. Following the failure of talks to get the group to relinquish violence, the government in Abuja has conducted a number of crackdowns. But it appears to be unable to confront the group that is attacking Nigeria on a new front almost every week.
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