The four were separated from their group and were told by their guide to follow the lights to the exit, a Cape Town resident told the SABC.
When the cave lights went out, the group was unable to find its way out.
A Cape Town woman was able to call the police using her cellphone. They were rescued by cave staff about an hour-and-a-half after the phone call.
Sorry to interrupt this "cellphones working in caves" discussion, but there seems to be a media discrepancy here (how unusual).
I tend to find the following version slightly more credible...
Tourists locked in Cango Caves
By Derrick Spies, Safety and Security Reporter, The Herald (South Africa)
8 January 2007
Four tourists were locked in the Cango Caves for two hours on Saturday evening, and had to phone the police to come and let them out.
A police spokesman confirmed that the four, South African Amanda Claasen, Italian Angelo del Parigi, and Argentines Carolina Ciranja and Damian Pertile, had been locked in and had used a landline telephone inside the caves to call the police.
Claasen said: “We had fallen behind the rest of the group. The guide told us to follow the lights, while she went to help some of the others,” she said.
Claasen said they had then followed the lights but soon came upon a part that they had already completed, and turned round to go in the opposite direction. Five minutes later, the lights went off.
“We shouted for help, but soon realised no-one could here us. It was pitch black and we used our cellphones to light the area,” she said.
Shortly after this, Claasen said, they had found the landline phone nearby, but some of the buttons stuck, so it took her over half an hour before she could dial 10111 to get the police.
“At first they didn‘t want to believe me, but eventually I convinced them that we were really locked in the caves, and they started phoning people at the caves to help us,” she said.
It took another hour-and-a-half before the four were rescued.
1001 uses and counting. Is there anything cellphones can't do?