Rescue workers found the bodies of six people who suffocated deep in an underground cavern on Spain's Canary Islands today, a spokeswoman said.
The six were part of a group of 30, including scientists and members of a nature organisation, who had been exploring caves on Tenerife today.
Most had managed to get out unaided, but eight were rescued in the early hours of the morning with acute breathing difficulties and were taken to a hospital. Rescuers found the last six in the afternoon.
There were five men and one woman, and one of the men was Italian. "I can confirm there are six dead, and we have recovered five of the bodies so far," a spokeswoman for the emergency services said.
She said the missing were 1,500 to 2,000 metres (5,000 to 6,500 feet) underground and access for rescue workers was very difficult.
The official cause of death would not be confirmed until there was an autopsy, but initially it looked like lack of oxygen rather than toxic gas, she said.
"The tunnels are very narrow. There is not much air and this was a big group," she earlier said. The underground labyrinths on the volcanic island of Tenerife, off the coast of Morocco, are known to some locals.
The Teide mountain on Tenerife is one of Europe's few active volcanoes.