KANO, Nigeria - Gunmen killed 15 people and wounded many more when they attacked a lecture theatre used by Christian worshippers in Nigeria's second largest city of Kano on Sunday, a university worker told Reuters.

The man, who asked not to be named, said he saw 15 bodies being carried from the site and many more being treated for injuries.

There was no immediate claim of responsibility for the attack but Islamist sect Boko Haram has killed hundreds in bomb and gun attacks this year, some of which have targeted churches.