One person has died and 23 people have been rescued after they were trapped hundreds of feet underground at the Mollie Kathleen Gold Mine, a tourist mine in Cripple Creek, Colorado, officials said Thursday.

Eleven people were rescued earlier Thursday. A dozen more people who came from out-of-state were trapped at the bottom of the 1,000-foot-deep mine for about six hours before being rescued Thursday night.

“I am relieved that 12 of the people trapped in the Mollie Kathleen Mine have been safely rescued. Our deepest condolences to the family and friends of the individual lost in this incident,” Colorado Gov. Jared Polis said in a statement Thursday night.

Among those rescued, two were children and four were seen by medical personnel for minor injuries, according to Teller County Sheriff Jason Mikesell, who did not provide details on the fatality.

At around noon Thursday, the mine experienced a mechanical issue with its elevator system, causing “a severe danger for the participants,” Mikesell said during a news conference. The cause of the accident remains under investigation.

As the dozen people trapped faced cold temperatures around 50 degrees, they had water, blankets, chairs and a radio. Facilities like restrooms, however, weren’t available underground, according to the tour website.

“We are thrilled to hear all 12 people who were still inside the Mollie Kathleen Gold Mine have been safely rescued,” the Colorado Springs Fire Department said in a social media post Thursday night. “We’re grateful for the work of all first responders who ensured the safety of those still inside. Our condolences go out to the family who lost a loved one tonight, please keep them in your prayers.”

The body of the deceased person had been recovered when the first group was brought up an elevator after being stuck halfway at 500 feet, according to Mikesell.

To rescue the last group, inspectors worked to ensure that the elevator was going to work properly so that they could bring them up on it, Mikesell said. They brought them up four at a time, he added.

“We did have a briefing with them to explain to them what was happeing because they were in this tunnel and didn’t know that any of this was going on,” Mikesell said.

The mine last experienced an accident in 1986, and it has been operating as a family-owned tourist attraction for “well over 50 years,” Mikesell said. In that accident, two people were trapped in an elevator, but no fatalities were reported.

The one-hour tour – an entirely underground experience that takes guests through the 1890s’ gold mine – “is not claustrophobic but, the descent in the shaft is very close for 2 minutes (each way),” the tour website states. The elevator moves at a speed of about 5 mph.

After going down the elevator, guests take a short ride on an underground rail car, then continue on foot for a quarter mile of flat and level walking and are shown how gold mining worked, according to the website. Guests are provided hard hats and are told to leave personal items like walkers and wheelchairs behind during the tour. The attraction was scheduled to close for the season this weekend before opening back up in the winter.