CHARLESTON, W.Va. (AP) — Their faces covered in black soot, three adults safely rescued after several days in an inactive West Virginia coal mine were mobbed by loved ones in a teary reunion, then they thanked the crews that got them out.

The three walked out of an ambulance at a fire hall in Whitesville to the screams of relatives for a brief reunion Wednesday night before being taken to a hospital.

Cody Beverly told news outlets the four-day experience inside Elk Run Coal’s Rock House Powellton mine near Clear Creek “was terrible.”

“I’m with my family now. I’m fine,” he said.

Beverly later told NBC News “Anybody who was involved in searching for us, I just want to thank you with everything inside of me,” he said. “This is the biggest lesson I’ve ever learned in my life. This is a life-changing experience for me.”

“We appreciate every one of you guys,” said Kayla Williams, who also was among those rescued.

Williams’ father, Randall Williams, said she had gone into the mine in search of copper.

People in the region do “whatever they can do to make money if they ain’t got a job,” Randall Williams told CBS News .

Raleigh County Prosecutor Kristen Keller said Thursday the sheriff’s office is conducting a criminal investigation into the latest incident. She said the two offices began discussing potential charges when the search began Sunday.

Sheriff Scott Van Meter didn’t immediately return a phone message seeking comment on the investigation.

Reports of people entering inactive mines in search of copper to sell are not uncommon.

Late last month crews abandoned their search at another West Virginia mine for a missing man suspected of stealing copper. Two other men who were arrested indicated the third man had gone inside a mine, but the search was called off after a team encountered unsafe conditions.

And earlier this month two men were arrested on charges that they broke into another mine in Boone County. Investigators said they, too, were looking for copper.

“It is a disturbing trend with people entering abandoned mines to steal copper wiring,” said Boone County Chief Deputy Chad Barker. “I can’t stress how dangerous this idea is and it’s only a matter of time before we get a less desirable ending.”

Abandoned coal mines contain toxic levels of gas, collapsing roofs, flooding, and other dangers may exist.

“When operations cease and a mine is sealed, conditions can deteriorate very quickly,” said Eugene White, director of the West Virginia Office of Miner’s Health, Safety and Training.

The latest search effort had prompted Gov. Jim Justice to issue a plea for people to stay away from nonworking mines.