A major rescue operation is underway to retrieve an American man who became trapped in a deep cave in Turkey over the weekend, officials said. Caver Mark Dickey, 40, was around 3,000 feet down in the Morca Cave—the third deepest cave in the country—on Saturday when he began suffering gastrointestinal bleeding. The Turkish Caving Federation said Wednesday that doctors had reached and treated Dickey. But he’ll likely still need to be stretchered out of the cave system, a process that experts have said could take days or even weeks. In a video shot inside the cave and released Thursday, Dickey said, “The caving world is a really tight-knit group and it’s amazing to see how many people have responded on the surface... I do know that the quick response of the Turkish government to get the medical supplies that I need, in my opinion, saved my life. I was very close to the edge.” More than 150 rescuers are involved in the operation, according to the caving federation.