Authorities stepped up security Monday as they launched a probe into multiple attacks that killed 20 people in northeastern Nigeria, including a bomb blast at a police barracks. The police barracks bombing killed at least 10 people Sunday evening in the troubled city of Maiduguri where Islamists are active. \"The area is still cordoned off by soldiers that have deployed all over the place, forensic experts are still combing the scene looking for some clues. No one is allowed in or out of the area,\" resident Awwalu Manu said by phone. Residents also reported a second blast near the city\'s main bus terminus, about an hour after the police bombing. \"There is a military checkpoint near the terminus and from all indications, it was the target of the attack,\" resident Jibo Mohammed told AFP. \"But fortunately it exploded some metres away and this led to shootout between the attackers who where on motorbikes and soldiers at the checkpoint,\" he added. Authorities could not immediately confirm the second blast. Hours earlier, a leading politician was shot dead in the same city, while police sources and residents reported a wave of shootings overnight Saturday that killed nine people, including three retired police officers. A special security unit was deployed in the city a week ago on orders of President Goodluck Jonathan. Anti-bomb squads have been deployed around key government buildings and military barracks. More road blocks have been erected and checks are more thorough than before to include patdowns of vehicle occupants. No-one has claimed responsibility for the weekend attacks but Boko Haram, an Islamist sect active in the region and blamed for most of the previous deadly attacks, is the prime suspect. Boko Haram wants to see the establishment of an Islamic state in northern Nigeria. On Sunday last week attackers set off three bombs and shot into the crowd at a crowded beer garden in Maiduguri killing 25 people and injuring as many. This weekend\'s biggest blast targetted a so-called mammy market beer garden at the police barracks. Mammy markets are open air pubs and eateries found around police or military barracks, open to both security personnel and civilians. Brigadier-General Jack Okechukwu Nwaogbo, the commander of a crack military unit deployed a week ago to curb the unrest in the area, said eight deaths had so far been recorded from the police blast. Hours before the attack, Mustapha Ba\'le, a politician of the state\'s ruling party the All Nigeria Peoples Party (ANPP), was shot and killed near his house in another part of the city, a senior police officer said. And overnight Saturday, gunmen went from house to house shooting their victims in targeted attacks, a senior police officer said on condition of anonymity. A civilian beer garden in the same city was bombed last Sunday leaving at least 25 dead and 30 wounded. Although no one has claimed responsibility for the attacks, they bore the hallmark of Boko Haram. The extremist sect has in the last year carried out bombings and shot dead leading figures targeting military and police personnel, community and religious leaders, politicians, churches and a prison. Boko Haram -- the name means \"Western education is sin\" -- launched an uprising in 2009 which was put down by a brutal military assault that left hundreds dead, most of them members of the sect.