Attackers have stormed a federal prison in Nigeria with heavy gunfire and explosives, killing one guard and freeing at least 118 inmates in a new assault, according to an official.
The details of the prison attack in Koton-Karifi, a town in Kogi state, just south of Nigeria's central capital Abuja, were announced on Thursday.
According to Kayode Odeyemi, the Nigeria Prisons Service spokesman, the men attacked just after 7pm local time on Wednesday, fighting through the prison gate and killing one guard in the process.
Al Jazeera's Yvonne Ndege, reporting from Abuja, spoke to witnesses who described the attackers as heavily armed and riding motorbikes.
"Witnesses said the group basically bombed its way into the prison, creating a scene of complete carnage. In the ensuing chaos, between 100 and 200 prisoners escaped," Ndege said.
Hadijha Aminu, a local prison official, said guards still had not completed a head count and did not know how many prisoners actually were inside the prison at the time of the attack.
The government said an investigation into the attack had begun.
"One does not really know why'' the men attacked, Odeyemi said. "It might be that some of the armed robbers are trying to free the armed robbers there awaiting trial.''
Odeyemi said he did not know if the prison held any members of the radical Islamist group known as Boko Haram, which has been plaguing the country with violence over the last year.
But Al Jazeera's Ndege said: "The belief is that they were trying to free Boko Haram suspects; there were about 20 Boko Haram suspects awaiting trial inside the prison."
Boko Haram launched a similar massive prison break in Bauchi state in September 2010 that freed about 700 inmates there.
The style of the attack on Wednesday, which apparently used explosives and heavy gunfire, matched that
previous assault by Boko Haram.
Members of the group have been blamed for killing at least 286 people this year alone, according to an Associated Press news agency count.
Boko Haram's violence comes as part of a campaign which its leader, Abubakar Shekau, says is aimed at avenging Muslim deaths, freeing imprisoned members and pushing for strict Islamic law across multi-ethnic Nigeria, a nation of more than 160 million people.
No group immediately claimed responsibility for the prison attack, and authorities no suspects were immediately in mind.
If Boko Haram carried out Wednesday night's attack, it would be the farthest strike south the group has made. Nigeria is largely split between a Christian south and a Muslim north.
Most of Boko Haram's previous attacks have taken place largely in the north.
Nigeria's prisons remain overcrowded and understaffed, with the majority of those imprisoned awaiting trials for years that likely will never come.
A 2007 study by Amnesty International, the UK-based rights organisation, called the system "appalling", with children remaining locked up with their parents and guards routinely bribed by inmates.
Despite pledges by the government to reform the system, it remains largely the same today.
Our correspondent said Thursday's prison attack will be another public relations setback for the government.
"Nigeria's security services are under tremendous pressure to control Boko Harem and this prison break will be a huge embarrassment," Ndege said.
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