At least 100 girls have been abducted from a secondary school in Borno state, north-eastern Nigeria, by armed militia on 14 April, sparking fears that violence in the region is out of control.

It is thought Islamist extremist group Boko Haram is behind the attack, which took place as the girls slept in their dorms in a school in Chibok. Although all schools in Borno have been forced to close due to increased fighting, the girls – all of whom are reported to be between 16 and 18 years old - had returned to complete their exams.

Boko Haram – which translates as 'Western education is sacrilege' - was officially labelled a 'Foreign Terrorist Organisation' by the US government last year. It has ties to Al-Qaeda, and is responsible for over two thousand deaths in Nigeria since 2009.

Its leadership has declared its intention to cleanse the country of Christians, eradicate Nigerian democracy, and replace it with an Islamic state guided by Sharia law, although members of the extremist faction have also begun targeting some Muslim communities which they believe to have betrayed Islam.

Late on Monday night, men armed with guns killed a policeman and soldier who were guarding the school and then forced entry into the dormitories, ordering the students to climb into open backed trucks, a state spokesperson said.

"Many girls were abducted by the rampaging gunmen who stormed the school in a convoy of vehicles," Emmanuel Sam, an education official in Chibok, reports.

Members of Boko Haram are known to abduct women and forced them into sex slavery and domestic servitude, and their leader Abubakar Shekau threatened to kidnap girls from schools in a video just last month.

However, several of the abducted girls were able to escape and make their way back to the school. Unconfirmed reports suggest that bodies were found in nearby woods.

The incident occurred just a few hours after an explosion at a bus station in Abuja, Nigeria's capital, during rush hour that resulted in at least 75 fatalities and a further 141 casualties. Boko Haram are also suspected to be behind this attack.

Reuters news agency reports that President Goodluck Jonathan immediately condemned the violence; criticising "the activities of those who are trying to move our country backwards".

"We will get over it...The issue of Boko Haram is temporary," he declared.

This week, Mervyn Thomas of Christian Solidarity Worldwide appealed to Christians and Muslims in the country to engage in peacebuilding efforts to counter Boko Haram's "divisive acts of appalling and indiscriminate violence".