The Nigerian Islamist sect Boko Haram is thought to have been behind a deadly siege on the northeastern town of Bama on Tuesday that left 55 people dead.
Military sources in Nigeria said 200 heavily armed members of Boko Haram arrived in buses and pick-up trucks and carried out a coordinated strike, first hitting the army barracks and the police station before breaking into the town's prison.
Military spokesman Sagir Musa told Reuters that 22 police officers, 14 prison officials, two soldiers and four civilians were killed in the five-hour raid, while 13 of the group's own members died. The attack is one of the rebel's most deadly single strikes since 2009.
During the five-hour raid, gunmen freed 105 prisoners, while the town's police station, army barracks and government buildings were reportedly set ablaze.
Boko Haram is a terror group that wants to carve out an Islamic state in a country split roughly equally between Christians and Muslims. One of its chief demands is that its imprisoned members and family members are released and it has carried out several prison breaks.
The radical Islamist group, based in northern Nigeria, once specialised in robbing banks and attacking defenceless Christian congregations. But the last four years has seen something of a step-change in their attacks, with gunmen and suicide bombers have killed more than 3,000 people since 2009, according to Human Rights Watch.
Much of this transformation is believed to have arisen because of the help Boko Haram has received from al-Qaeda in the Islamic Maghreb (AQIM), a branch of the international terrorist network based in the Saharan states of Mali, Niger and Algeria.
Western governments are increasingly concerned about Nigerian militants linking up with other jihadist groups in the West African region. In January at least 100 of the movement's fighters executed eight assaults in Nigeria's northern city of Kano, overwhelming the security forces and killing 185 people.