Swiss tunnel inferno kills 10

AIROLO, Switzerland -- At least 10 people have died in an accident involving two lorries in the world's second-longest tunnel, officials have said.

Dense smoke and high temperatures hampered rescue workers for several hours as they fought to reach the trapped motorists in the 10-mile-long Gotthard tunnel.

Both trucks had caught fire after colliding head-on, quickly filling the tunnel with black smoke and creating zero visibility.

Explosions could be heard, and part of the ceiling collapsed, Ticino state police spokesman Mario Ritter said.

One of the lorries was laden with tyres, and the thick smoke was feared to be toxic. Nearby residents were told to stay indoors with their windows closed to avoid breathing the smoke being belched out of ventilation units.

German journalist Elmar Herger toldl CNN: "The problem basically is that because there are just two roads in the tunnel (one road in, one road out)... if you have to get rescued there is a problem, you cannot get out.

"There are some rescue places in there but the problem this time is that it was so hot in there, there were flames all over, it was sort of smoke all over, so people couldn't get out, that was the problem."

Four helicopters and 150 workers are at the scene working to free those still inside.

The accident in the main north-south European axis through the Alps happened at 9:45 a.m. (0845 GMT) on Wednesday about a mile from the southern exit, Ticino state police added.

One of the drivers managed to escape, but the other is thought to have been one of the victims.

Others who managed to escape had run by foot out of the tunnel, with several being treated at an Airolo hospital for minor injuries, Ritter said.

Police at the northern end of the tunnel were able to turn many vehicles around and send them back to the northern exit, said Karl Egli, spokesman for Uri state police.

Traffic in the tunnel had increased since 1999 following the closure of the Mont Blanc tunnel after a blaze in which 39 people died.

The Swiss government said 1.2 million trucks passed through the Gotthard tunnel last year

The tunnel was expected to remain closed for the rest of the day, a police spokesman said.