Rescuers descended into a deep cave to rescue a trapped dog -- then they found a bear

Firefighters encountered an unexpected challenge while rescuing a dog trapped in a Tennessee cave: A black bear was also there.

The dog, Charlie, spent three days trapped nearly 40 feet deep in an "extremely narrow cave shaft" on English Mountain in eastern Tennessee, according to a Facebook post from the Waldens Creek Volunteer Fire Department.

A rescue team consisting of "rope rescue technicians" from several fire departments set off on the mission to free Charlie on Tuesday, the Facebook post says. The team hiked to the mouth of the cave, where firefighter Tori Downing and captain Jon Lanier descended into the cave.

"Things took a turn when Firefighter Downing rounded a corner and found a bear sleeping five feet below her and the trapped hunting dog farther in the cave system," reads the Facebook post.

Charlie's unwitting companion was a 2-year-old black bear weighing an estimated 200 pounds, according to the Waldens Creek Volunteer Fire Department.

The rescue team left the cave and set up trail cameras to track when the bear left the cave, the Facebook post says.

On Wednesday, they determined that the bear "had left the cave and not returned."

With the cave "bear-free," the stage was set for Charlie's rescue. Three firefighters descended into the cave on a rope system. But initially, it seemed they would still be unable to retrieve the trapped canine.

"At first, we actually thought the dog had slipped further into the cave where we couldn't access," Lanier said, according to CNN affiliate WVLT. "It was kinda sad because we felt like we were gonna have to leave the dog there."

"As we're about to head back out, I looked back one more time and I saw his antenna from his tracker collar," another firefighter, Christian Ellard, said, according to WVLT.

Charlie was "dehydrated and hungry, but in otherwise good condition," says the Waldens Creek Volunteer Fire Department.

The rescue team "fashioned a harness for the dog and effected the rescue," the department explained. "Charlie was quickly reunited with his happy owner."

The department included a photo of a volunteer emerging from the narrow cave mouth with Charlie in his arms and a shot of the rescued pup with four members of the rescue team.

"It was definitely a sigh of relief for everybody on scene," said Andrew Wojturski, a firefighter with Sevier County Fire & Rescue, according to WVLT. "And then once we finally got him out and the owner came up afterwards and shook our hands and thanked us, it was really rewarding."

In their Facebook post, the Waldens Creek Volunteer Fire Department thanked "the entire rescue team and people who worked together to make this happen."

"It was truly a team effort that required all these departments to make it a success," they said.

English Mountain is near Tennessee's Great Smoky Mountains National Park, described by the National Park Service as "one of the largest protected areas in the eastern United States where black bears can live in wild, natural surroundings." An estimated 1,900 bears live in the park.