Some officials of the Nigerian Correctional Service in Plateau state came under attack around a court in Barkin Ladi Local Government Area of the state on Thursday.
According to TheCable, the officials were taking the suspects to the state High Court in Barkin Ladi when they were attacked.
A source said three suspects were freed after the gunmen opened fire on the prison officials.
It is unclear if anyone sustained injuries in the attack.
Obah Ogaba, spokesman of the Plateau state police command, confirmed the incident to TheCable, saying investigation is ongoing.
Ogaba said Edward Ebuka, the commissioner of police, led some of his men to the scene shortly after the incident.
He refused to comment on the number of suspects who were freed in the attack which is the second major one in the town in 24 hours.
On Wednesday, a private security guard was shot dead during an attack at General Hospital, Barkin Ladi.
Three persons, including an official of the hospital and a police officer, sustained injuries in the incident.