ABUJA - Two suicide bombers attacked the University of Maiduguri located in the capital of Nigeria's northeastern state of Borno early Monday, killing at least five people and injured more than 15, local police said.

Borno State police chief Damian Chukwu said that a seven-year old boy detonated his improvised explosive device at a mosque located inside the Senior Staff Quarters in the university premises.

The explosive device of the first suicide attacker went off when he was gunned down by a mobile police officer on duty who sighted him while trying to scale the fence at one of the gates of the university, he said.

Satomi Ahmed, a coordinator of the Borno State Emergency Management Agency, said a professor who was director of veterinary at the university was among the five people killed in the attack. Four students were also killed, he said, adding rescue operation was still ongoing at the university premises.

Terror group Boko Haram, which has killed more than 20,000 and displaced 2.3 million people since the current insurgency started in 2009, is believed to be responsible for the suicide attacks.

Nigeria has made considerable gain on the Boko Haram front, with its security forces operating in the restive region dislodging the Boko Haram fighters from the Sambisa Forest, their last enclave in the country.