Attackers armed with bombs and guns opened fire at church services at a Nigerian university on Sunday, killing around 20 people as worshippers tried to flee, said witnesses and officials.

Explosions and gunfire rocked Bayero University in the northern city of Kano, with witnesses reporting that two church services were targeted as they were being held on campus.

One of the services was being held outdoors, while the second was inside a building, but with an overflow audience outside, said witnesses.

The military, which regularly downplays casualty figures, put the death toll at seven. However, an AFP correspondent counted six bullet-riddled bodies near one of the two sites.

At least another dozen bodies could be seen on a roadside by the university, but the exact number was unclear. An emergency official said another 22 people were being treated for injuries, mainly gunshot wounds.

Musical instruments and half-eaten meals could be seen left behind at the site of one of the services.

Witnesses said the attackers arrived in a car and two motorcycles, opening fire and throwing homemade bombs, causing panic. They said worshippers were gunned down as they sought to flee.

“They first attacked the open-air service outside the faculty of medicine,” said one witness. “They threw 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.”

There was no immediate claim of responsibility, although the attack was similar to others carried out by the Islamist group Boko Haram.

Boko Haram claimed January 20 attacks in Kano, the largest city in Nigeria's mainly Muslim north, when coordinated bombings and shootings left at least 185 dead in the extremists' deadliest attack yet. — AFP