Tuesday night's attack is thought to have been carried out by Boko Haram, which means "Western education is sin" in local Hausa dialect, a Muslim fundamentalist group fighting for the creation of an Islamic state in Nigeria. Mohammed Ahmed, the prison warden, said: "The prison had 762 inmates at the time of the attack. 732 escaped, leaving 30. All the Boko Haram suspects on remand have escaped. There were 150 of them."
The gunmen killed four people including a soldier, a police officer and two local residents.
Salisu Mohammed, a prison guard, described how up to 50 Islamist militants, armed with machine guns, attacked the jail..
"They came in large numbers, heavily armed, and began shooting at the prison gate. Some of us were hit while others fled," he said.
"They gained access and moved from cell to cell, breaking in and freeing the inmates. They set fire to a section of the prison and burnt the vehicles parked outside the gate."
Isa Hassan, a local resident, said the alleged sect members were chanting "Allahu Akbar" - or God is great - when they arrived.
"They shot dead a handful of policemen at the gate and forced their way in. From my house, I could see bodies and injured being loaded into a truck," he added.
"There was heavy fighting between the attackers and the security forces which lasted for almost an hour. It was quite terrifying," Usman Ahmad, another resident, said.
Locals said calm returned to the area on Tuesday night, though military and police were occasionally firing into the air as they locked the area down.
The attack is seen as a sign that Boko Haram is preparing to strike again in Nigeria, Africa's most populous nation, which roughly divided in half between Christians and Muslims.
The sect, often descibed as the "Nigerian Taliban", launched an uprising by last year with attacks on police posts. Police officers have been among the victims of a new wave of attacks by motorcycle-riding gunmen in northern Nigeria.
The uprising was crushed by a police and military assault, with the sect's headquarters and mosque left in ruins.
Nearly 800 people were killed, many of them shot by the security forces, in gun battles which raged for days as the police and army fought to put down the uprising by sect members armed with home-made guns, machetes and knives.
Tuesday's attack came on the same day officials announced January 22 as the date for Nigeria's presidential vote and occurred just before the end of the Muslim fasting month of Ramadan.
