Explorers die in Canary Islands tunnel after apparently suffocating

LOS SILOS DE TENERIFE, Canary Islands -- A group of 30 scientists and nature lovers got lost in a maze of narrow underground tunnels in Spain's Canary Islands, and six of them died after apparently suffocating, officials said Sunday.

The explorers were more than a mile underground Saturday in area where gases may have seeped in, cutting off their oxygen, said Jose Andres Garcia, the island's emergency services director.

Eustaquio Villalba, a spokesman for the Tenerife Friends of Nature Association, said the six likely died when they inhaled air filled with carbon dioxide.

"It doesn't smell bad or of gas and causes a depletion of what little oxygen is available down there, given there is no ventilation," he said.

One person who managed to make it out alerted emergency services, said Jose Miguel Ruano, Tenerife's regional government minister. But it took 17 hours for the bodies of five men and a woman to be pulled from the underground complex, known as Piedra de los Cochinos, on the island of Tenerife. Six others were flown by helicopter to a hospital.

Rescue efforts were complicated by the gases and because the tunnels are so cramped, Ruano said. Some are centuries old and have few stairs or lights. The area where the dead were found may have been just three feet in diameter.

Officials discourage exploration of the tunnels, carved out to extract water in the volcanic island off the west coast of Africa, said Jose Segura, an Interior Ministry official. But he said there is almost no way of policing the tunnels, and adventurers are lured by their beauty, including underground waterfalls. Authorities have erected steel gates to keep people out of some of the tunnels, but some have been broken open.

The group probably got lost because they ventured in without their guide, who had to cancel and give them instructions by cell phone before their descent, said Eustaquio Villalba, a spokesman for the Tenerife Friends of Nature Association.

Heikki Viironen said his daughter Terttu, a Finnish astronomer, was among those who made it out unharmed. Her Spanish companion was hospitalized. The couple found a stray dog that might have helped them find their way out, he told the Finnish news agency STT.

"We thought perhaps the dog's sense of direction saved them," Viironen said.

Among the group were scientists from a renowned astrophysics observatory on Tenerife's dormant Teide volcano, Ruano said. Others were members of the Tenerife Friends of Nature Association.

An Italian was among the dead, the Italian foreign ministry said. The Italian news agency said the man lived in Santa Cruz, the capital of Tenerife.

Villalba said in some parts of the tunnels, humidity can reach 100 percent and temperatures can reach 86 degrees.

"However, it can be spectacular, with underground waterfalls visible," he said.