A Pennsylvania man was hospitalized after he was freed from one of the nation's deepest caves after a nearly 24-hour rescue effort.

The caver was rescued Monday afternoon from Ellison's Cave in Walker County, Ga. and hospitalized in Chattanooga, Tenn., The Atlanta Journal-Constitution reported.

The caver was in critical condition after being flown by helicopter to Erlanger Medical Center, WDEF-TV reported.

He fell 40 feet down a cave that's the 12th deepest and considered one of the most difficult to navigate in the country, David Ashburn, who helped coordinate the rescue, told The Chattanooga Times Free Press.

The ordeal began Sunday, when four cavers were deep inside the cave when one of them fell more than 50 feet down a vertical drop, authorities said.

One of the cavers climbed out to call for help while the two remaining cavers in the group climbed down to reach their injured partner and try to stop his bleeding. Ashburn said his injuries included an obvious open fracture of his femur, a large bone in the leg.

“He's got a cut to his head with probably a skull fracture at the base of the skull based on the way he looks,” Dr. David Wharton of Erlanger told WDEF. “He got progressively more confused as he was coming out and so we were definitely concerned he could have a bleed in his head that could kill him.”

Rescuers gave the man a blood transfusion in the cave to keep him alive while they figured out how to get him out, WRCB-TV reported.

“They took, to a large extent, the emergency room to him and that's why he's in the condition to the level he is right now surviving in this,” Ashburn said.

Ashburn said many rescue crews aren't qualified to perform rescues in the cave because of the skill level required to navigate it, so experts from Alabama and Tennessee were requested.

More than 100 experienced cave rescuers from across the region drove to the site to assist in the effort in the hours after rescue crews were called around 6 p.m. Sunday.