At least 14 people were killed and 39 injured in multiple blasts which rocked parts of Nigeria's Maiduguri city, capital of Borno state, the army said on Friday.Four explosions took place on Thursday night in Sajeri and Dalla areas, acting spokesman of the Nigerian army Kukasheka Sani Usman said. Two explosions went off in each area, Xinhua news agency reported.Four Boko Haram suicide bombers carried out the attacks by detonating their explosives-laden vests, said the spokesman, adding the fourth explosion occurred in front of a local mosque.A hospital source said the toll might rise as some of the injured are in critical condition.