The rescue operation got underway at 4am
Four of the 12 boys trapped in a cave in Thailand for a fortnight are now in hospital.
The head of the rescue operation says they need at least 10 hours to prepare to bring the rest out - and their football coach.
90 divers are involved.
Officials say they need up to 20 hours to prepare for the next phase of the operation.
The dangerous mission to get the 12 boys and their coach out through narrow, water-filled tunnels began earlier.
The operation was launched at 4am today after local media was cleared from the area.
Helicopters are on standby ready to bring the young boys to hospital.
Torrential rain has been falling and the monsoon threatens to raise the water level in the cave which could hamper the rescue operation even further.