Johannesburg – Rescue teams have started pumping compressed air into the shaft where five mine workers are trapped 3.1km below ground in the Kusasalethu mine in Carletonville, a Harmony Gold spokesperson said on Friday night. This would reduce the risk of the miners suffocating while rescue operations are underway, Marian van der Walt told News24.Four rescue teams would work in shifts throughout Friday night and Saturday morning to ensure the safe return of the miners.The five miners were trapped behind a rock wall after a tremor, measuring 1.2, caused sections of the mine to collapse at 10:30 on Friday morning. It is unclear how thick the rock wall is.Van der Walt said the tremor could either be geological or mining-induced. This would be determined after the rescue operations.Rescuers had so far managed to talk to one of the trapped miners through a wall on Friday afternoon. About 3000 miners were working at the mine at the time of the tremor. No other injuries have been reported.