Iraqi officials announced ISIS staged the prison break in Iraq on Saturday in which 50 inmates and a dozen of policemen were killed.
ISIS fighters have claimed the responsibility for the jailbreak.
"ISIS was responsible for the killings and the release of ISIS prisoners," said Oudi al Khadran, mayor of the town where the prison is located.
Iraqi Interior Ministry spokesperson Brig. Gen. Saad Maan Ibrahim said a fight broke out among the inmates, and police officers who were responding to the disturbance were overpowered and had their weapons taken from them.
He said 40 inmates managed to escape the Khalis prison in Diyala in the attempt.
Ibrahim stated that some of the escaped inmates were individuals on a terror list and that a military search effort had begun.
Jailbreaks are common in Iraq where militant groups often detonate the walls or shell prison facilities in order to free incarcerated members of their groups.