The death toll following violence over the past two days in northern Nigeria has risen sharply from seven to 46, medical sources said on Saturday. The attacks which saw northern cities rocked by explosions and gunfire were claimed by the Islamist group Boko Haram, according to a purported spokesman, Gabu Kaka, who spoke to AFP. \"We are responsible for the attacks in Maiduguri, Damaturu and Potiskum. We carried out the attacks to avenge the killings of our brothers by the security forces in 2009. We will continue to wage war against the Nigerian state until we abolish the secular system and establish an Islamic state\". Nineteen bodies were taken to the morgue of a hospital in Damaturu while another 20 were counted at a morgue in Maiduguri after violence broke out in the two cities and in Potiskum, the sources said. A Damaturu resident on Thursday said it appeared that suspected members of Boko Haram were in the streets shooting and setting off explosions at random. Residents in Maiduguri said people were fleeing and one of six explosions there had shattered the windows of a mosque in an office complex. Maiduguri has borne the brunt of the violence attributed to Boko Haram, which has claimed responsibility for scores of attacks in the north as well as the August suicide bombing of UN headquarters in the capital Abuja that killed at least 24. More attacks took place in Damaturu on Friday.