Members of the fire services battled for more than three hours to extinguish a fire that had engulfed part of the Mmabatho police station in North West at the weekend.
Captain Lesego Metsi said the smoke in the kitchen was noticed by members of the police who were on duty at about noon on Sunday.
Members of the fire brigade were called as the fire threatened to spread to the adjacent cells holding several awaiting-trial prisoners.
When Sowetan visited the police station early yesterday, the roof of the station's kitchen had caved in.
Metsi said they did not suspect any foul play or a plan by the inmates to escape.
"We are still waiting for the forensic experts to determine the cause of the fire. We suspect it was caused by electrical problems or the gas stove used for cooking, but we cannot say so conclusively at the moment."