Updated

Rescuers were working Monday to bring out a man stuck deep inside a cave in the German Alps after he was injured by falling rocks, an effort that police said could take days as experts negotiate a tricky labyrinth of vertical shafts and bottlenecks.

A four-member rescue team reached the 52-year-old German cave researcher early Monday inside the Riesending cave system, near Berchtesgaden in Germany's southeastern corner, police said.

The man, whose name wasn't released in keeping with German privacy rules, had suffered head and upper body injuries a day earlier. One of his two uninjured companions made a 12-hour climb back to the cave entrance to alert authorities, while the other stayed with him.

The injured man is nearly 3,300 feet underground "in one of the most difficult caves in Europe," mountain rescue official Klemens Reindl told n-tv television.

"We have shafts that go straight down 1,150 feet, where you have to rappel down and climb back up on a rope," he said. The cave system has tight spots where only a slim person can squeeze through, and explorers also have to contend with water, the mountain rescue service said.

Rescuers laid a telephone line several hundred meters deep on Monday to help the rescue effort, while others set up camps inside the cave system on the border with Austria. They were working in several small teams of up to four people each.

Some 52 cave rescue specialists from Bavaria and another 28 from Austria were at the scene.