ABUJA - Nigerian soldiers blanketed the town of Bama on Wednesday, where residents stayed indoors after coordinated assaults by heavily armed Islamist insurgents killed 55 people.

The military said the brazen raid was carried out by some 200 gunmen from the extremist group Boko Haram, who stormed the town in a convoy of buses and 4x4 trucks, armed with machine guns and rocket-propelled grenades.

Disguised in army uniforms, the insurgents broke into a prison, killed 14 guards and set free 105 inmates, the military in northeastern Borno state said.

They attacked a police station, killing 22 officers, while 13 Islamists, four civilians and two soldiers were also reported to have lost their lives in the assaults that paralysed the trading town.

"Only a few people have ventured beyond their front doors,” said Bama resident Musa Bra. "Troops are all over the town patrolling the streets.”

He explained that many people fled to the bush after the pre-dawn attack on Tuesday.

While some have tried to return, the military is screening everyone entering the town and asking for proof that they are civilians and not members of the insurgent group which has become notorious for blending in with the local population, Bra further said.

"Everybody is indoors,” said another resident who asked that his name be withheld. "It is just military all over the town.”

A journalist who visited Bama on Tuesday said shops, petrol stations and markets had shuttered, and there were burnt vehicles by the roadside.

Borno state is a Boko Haram stronghold and has seen scores of attacks since the group relaunched its insurgency in 2009. 

Islamic state

But the violence has intensified in recent weeks.

Last month in the town of Baga, northeast of Bama and also in Borno state, brutal clashes between Boko Haram and Nigerian troops killed nearly 200 people, the deadliest-ever episode in the insurgency.

Soldiers have been accused of causing scores of deaths by deliberately setting fire to much of the town, a charge the military has fiercely denied.

The authorities have voiced increasing concern that Boko Haram has fostered closer ties with other extremist groups operating in the region, including Al-Qaeda’s North Africa affiliate.

Agencies