Explosions and gunfire have been heard across the northeast Nigerian city of Gombe, previously targeted by a radical sect, as authorities in another city blamed its members for killing five people leaving a mosque. Gunfire followed the explosions, with witnesses saying people began fleeing the area near a police command and an immigration office. Gombe state police commissioner Orubebe Ghandi Ebikeme simply described the situation as \"very bad\". No group claimed responsibility for the attacks, though suspicion immediately fell on the radical sect known as Boko Haram. Boko Haram is carrying out increasingly sophisticated and bloody attacks in Nigeria, a multiethnic country of more than 160 million people. The sect has been blamed for killing at least 310 people this year alone. Boko Haram, whose spiritual home is in neighboring Borno state, has carried out attacks in Gombe state before. In January, suspected sect gunmen attacked a church in the city during a prayer service, killing at least five people and wounding others. Meanwhile on Friday, authorities blamed gunmen from Boko Haram for killing five people leaving a mosque after evening prayers. The attack happened in Kano, a city of nine million people where the sect killed at least 185 people last month, said Magaji Musa Majiya, a local police spokesman. Majiya said officers had not made an arrest in the killings as of late Friday night.