More than 180 inmates in a medium-security prison in central Nigeria were at large after unidentified gunmen opened fire on the facility, the government said on Monday.
The attack happened late Sunday at the jail in the Tunga area of the Niger state capital, Minna. Guards were overpowered and inmates were able to escape.
"Out of the 210 inmates that escaped from prison custody, 28 have been re-arrested while 182 are still at large," Nigeria's interior minister Abdurrahman Dambazau told reporters.
"We have identified some lapses... part of it is that the prison personnel on duty yesterday were inadequate," he said after touring the prison.
An investigation has begun but it was not immediately clear who or what was behind the incident.
Periodic jailbreaks occur in Nigeria's congested and poorly maintained prisons, mostly aided by criminal gangs to free their comrades.
In November 2014 a group of gunmen armed with explosives blasted a prison in the town of Koton Karfe, in Kogi state, which neighbours Niger to the south: 132 inmates escaped.
In 2012 the same prison was raided by gunmen who freed more than 100 inmates. Boko Haram Islamists claimed responsibility and said its fighters were being kept in the facility.