Of the 18, two are on life sentences, while one is on death row.
Commissioner Pokanis appealed to citizens and residents in the immediate areas of the prison to report any sightings or whereabouts of the escapees, and contact the police.
Pokanis said, "While the prisoners were having their activities during the repentance day, these 18 decided to escape."
The CS Commissioner also clarified that the duty officer was not on site when the incident happened. An investigation will be conducted into this.
Seven-hundred and thirty prisoners were on site when the incident happened.