Around 20 gunmen believed to be members of the Boko Haram militant group raided a federal prison in Nigeria on Wednesday night, freeing as many as 200 inmates before escaping in getaway vehicles.

The jailbreak took place at the Koton-Karfe prison in the central Kogi State. At least one prison guard was killed during a 30-minute long gun battle

They opened fire on one of the security men at the entrance of the prison and killed him on the spot, witness Mariamu Bello told Deutsche Presse-Agentur. The main gate of the prison was bombed by the Boko Haram members.

Boko Haram is a rebel Islamic sect that has been tearing across Nigeria for nearly two years. The group, whose name translates as Western education is a sin, has been becoming increasingly lethal in recent months and has carried out a number of attacks, primarily in the Muslim-dominant northern part of the country.

The insurgents killed about 500 people in 2011 and already an additional 200 in the first two months of 2012.

However, Nigeria Prisons Authority spokeswoman Hadiza Aminu denied the Islamic sect was involved in the attack -- saying the gunmen were from a local robbery syndicate -- but witnesses and local reporters are convinced that Boko Haram was responsible.

According to reports, some Boko Haram members were freed in the raid. The group has not claimed responsibility for the attack.

Jailbreaks are part of Boko Haram's original modus operandi. The first major Boko Haram attack was the September 2010 Bauchi prison break, when a group of 50 gunmen freed more than 700 prisoners in the northern Bauchi state.

Since then, the group has at times broken its members out of jail -- before Thursday's attack, the most recent such incident was the escape of Kabir Sokoto, the main suspect for the Christmas Day church bombings that killed more than 50 people.

Boko Haram generally launches attacks in the north, however it has extended its activities as far south as Abuja, the capital city, and into the central Niger state. There are also a number of militant groups operating in Nigeria's oil rich Delta region.