Three suicide bombers, including a child, exploded at dawn Monday at Nigeria's northeastern University of Maiduguri, killing a university professor and another child, witnesses and police said. The bombers also died.

One blast ripped through the mosque where professors were saying dawn prayers and at least one is among victims, police and rescue officials said.

The second explosion occurred when police patrolling the back of the university shot a 12-year-old girl strapped with a suicide vest, setting off the explosives, according to police spokesman Victor Isuku.

He said 15 wounded people were evacuated to hospitals. The National Emergency Management Agency which carried out the evacuations put the wounded at 17.

Maiduguri has been attacked many times but this is the first attack on the university blamed on Boko Haram - the Islamic extremist group whose name means "Western education is sinful."

President Muhammadu Buhari sent condolences to the families of victims and said the attack on a place of learning shows the perpetrators "have no true understanding of Islam." Buhari, a Muslim, promised his administration "will continue to ensure that terrorism never triumphs over peace-loving Nigerians."

Monday's is the first major attack since Buhari last month declared that Boko Haram was "crushed," after troops destroyed their stronghold in the Sambisa Forest in northeastern Nigeria.

Nigeria's army said Sunday that troops continuing "clearance operations of remnants and fleeing Boko Haram terrorists" killed several insurgents and rescued 58 kidnap victims, mainly women and children last week. One soldier was injured, it said.

A separate statement Friday said three soldiers and 10 Boko Haram fighters were killed when the insurgents attacked an outlying army post in northern Borno state.

Nigeria's 7-year-old Islamic uprising has killed more than 20,000 people.

AP