Nigerian soldiers pictured at a military camp in Maiduguri, the capital of the north-eastern state of Borno, on June 6, 2013
Maiduguri (Nigeria) (AFP) - At least 28 people were killed in a suicide bombing at a mosque in Maiduguri, northeast Nigeria, on Friday, raising fresh security concerns after a wave of similar attacks.
The attack happened shortly after 5:00 am (0400 GMT) in the Jidari area of the Borno state capital, which has previously been targeted by Boko Haram militants.
Maiduguri has now been hit six times this month, killing a total of 76 people, according to an AFP tally, underscoring an increased risk to civilians after similar strikes in neighbouring states and near the capital, Abuja.
Umar Sani, a civilian vigilante assisting the military in the counter-insurgency, and local resident Musa Sheriff both told AFP there were two blasts at the mosque.
"People from various mosques nearby rushed to the scene to assist the victims," said Sani.
"I was involved in the evacuation. We counted 28 dead bodies apart from the two bombers, who were identifiable by the mutilation of their bodies.
"Over 20 other people were injured."
Sheriff, who said he escaped with his life as he was late for prayers, gave a similar account.
Both men also said two other people were arrested and handed over to the military for questioning after they were seen apparently celebrating following the blasts.
The two men were "standing from afar, hugging each other like a celebration, chanting "Allahu Akbar" (God is greatest)", said Sani.
"The rescuers apprehended them. They used ropes to tie them and they confirmed that two of their comrades carried out the attacks. They were unrepentant," he added.
"To them it was a mission accomplished," said Sheriff.
- Security concerns -
Initial reports of the attack from Nigeria's National Emergency Management Agency (NEMA) said only six people were killed and 17 others injured.
Medical sources at the University of Maiduguri Teaching Hospital and Borno State Specialist Hospital later gave a lower toll of 19 dead.
There are frequently conflicting death tolls in the insurgency and official statements often downplay the number of casualties.
Nigeria's military has claimed a series of successes against Boko Haram, recapturing territory seized by the militants last year, as well as the mass surrender of fighters.
Senior officers have characterised the increase in suicide bombings against "soft" targets as a sign of the group's desperation.
Nigeria's President Muhammadu Buhari has said the military is on track to meet a year-end deadline to bring the six-year insurgency to an end.
At least 17,000 people have been killed and more than 2.5 million made homeless by the violence, which has spread into neighbouring Niger, Chad and Cameroon.
But the latest bombings in Maiduguri will likely raise questions about how militants are able to carry out such attacks on a regular basis.
Friday's attack fits into a grim pattern of targeting places of worship and crowded spots such as markets and bus stations using multiple bombers to maximise casualties.
On October 1, a wave of suicide and bomb attacks left 10 dead in the Ajilari Cross area of the city, which was hit again on October 13, killing four.
On October 15, two suicide bombers hit a mosque in Molai, on the outskirts of Maiduguri, killing 30.
The following day, three bombers also struck just before morning prayers in nearby Umarari. Four people were killed.
Last weekend, soldiers foiled a suspected suicide attack at the city's main army base.
Boko Haram -- using the name Islamic State West Africa Province -- claimed responsibility for suicide bomb attacks near Abuja on October 2 that killed 18.
Five men appeared in court on Thursday in connection with the blasts.