Suspected Islamist militants launched a brazen daytime attack Friday in the northeastern Nigerian city of Maiduguri.
Witnesses say gunmen armed with explosives stormed the Giwa military barracks early morning local time, setting off a fierce gunbattle with soldiers. The attackers also set fire to homes in a residential area and opened fire on civilians.
Nigeria's defense ministry says "pockets of terrorists" attacked the barracks in an apparent attempt to free "colleagues" detained at the site.
In a statement, a defense official says they attack was "successfully repelled," with the terrorists suffering heavy casualties. The official says four soldiers were wounded during the incident.
A local reporter told VOA that some detainees escaped from the barracks, which are used as a holding facility for suspected militants facing trial.
The reporter says a local paramilitary force has joined efforts to hunt down the escapees. The reporter also says that bodies littered the ground near the site of the attack.
There was no immediate claim of responsibility.
Maiduguri is the home city of the Islamist radical sect Boko Haram. The group is blamed for thousands of deaths in Nigeria since 2009.
On Friday, Human Rights Watch said Boko Haram had launched attacks in over 40 villages in northeastern Nigeria since the the start of 2014.
The rights group says the militants have carried out "almost daily killings, bombings, thefts" and other crimes that have led to the deaths of 700 people so far this year.
Efforts by the Nigerian military to stamp out the group have not stopped the violence.
Friday's suspected militant attack took place as U.N. High Commissioner for Human Rights Navi Pillay was visiting the Nigerian capital, Abuja.
Pillay said the alleged Boko Haram attacks had "grown increasingly monstrous."
However, Pillay also said many people had told her that Nigerian security forces had been committing human rights violations that were alienating communities and creating "fertile ground" for Boko Haram recruiting efforts.