Dozens of prisoners broke out of their cells and tried to escape early Monday morning as Nigerian authorities battled with gunmen at a police station on the edge of Abuja.
Two officers were killed during the gunfight, police spokesman Frank Mba said in a statement. Thirty prisoners broke free during the melee, Mba said, but all but five were returned to custody thanks to "tactical and coordinated efforts." Two suspected members of the "large number" of attackers were also arrested, according to the police statement.
Though police said the five escaped prisoners had been held on robbery, not terror, charges, the attack echoes assaults by Boko Haram, an Islamist extremist group that has terrorized Nigeria with bloody raids against police, churches and schools. Criminal gangs have also waged violent attacks in the country. No group had claimed responsibility Monday for the attack.
Police inspector-general M.D. Abubakar ordered an investigation into the assault and "watertight security" around all government and police facilities nationwide. Past escapes from police custody have spurred suspicions of corruption and infiltration of security agencies.
The attack on a special anti-robbery squad comes one day after twin suicide bombings at a church inside a military barracks in northern Nigeria. The death toll in the Jaji bombings has risen to at least 30 people, a hospital official told the Associated Press on Monday.
As attacks continue, the International Criminal Court prosecutor has found "there is a reasonable basis" to believe that Boko Haram has carried out crimes against humanity, including murder and persecution, according to a report shared with the media this weekend. It recommended that the court take the next step of assessing whether Nigerian authorities are pursuing those responsible for the crimes.
Though the report also noted killings and abuses by mobs and other militant groups in the country, along with alleged torture by security forces, it said there wasn't enough information or evidence to classify them as crimes against humanity or war crimes.