Twelve people were rescued on Thursday night after being trapped for about six hours at the bottom of a former Colorado gold mine when an elevator malfunctioned at the tourist site, leaving one person dead.

The elevator was descending into the Mollie Kathleen Gold Mine near the town of Cripple Creek when it had a mechanical problem around 500 feet (150 metres) beneath the surface, creating a “severe danger for the participants”, and one person was killed, Teller County Sheriff Jason Mikesell said.

The 12 adults who were trapped were about 1,000 feet (305 metres) below ground, but they had access to water and the atmosphere was considered good. They were safe and in communication with authorities with radios while waiting, Mr Mikesell said.

They were in good spirits after they were rescued, and authorities gave them pizza once they were out and told them everything that had happened, he said. While at the bottom, authorities had told them only that there was an elevator issue.

Mr Mikesell said during a night-time briefing that authorities do not know yet what caused the malfunction and an investigation is underway.

Colorado Gold Mine People Trapped
Emergency personnel stage outside the Mollie Kathleen Gold Mine (Arthur Trickette-Wile/The Gazette via AP)

Engineers worked to make sure the elevator was working safely again before bringing the stranded visitors back up on it. They had been prepared to bring them up by rope if necessary, had they not been able to get the elevator fixed.

Mr Mikesell declined to reveal the identification of the victim.

The incident, which was reported to authorities at about noon, happened during the final week of the Mollie Kathleen Gold Mine season before it shuts down for the winter, Mr Mikesell said.

Earlier in the afternoon — while the 12 were stuck at the bottom — 11 other people who were riding the elevator were rescued. Four had minor injuries. The sheriff did not elaborate on how they were injured.

The elevator ride typically takes about two minutes, travelling about 500 feet (152 metres) per minute, according to the mine’s website.

Mr Mikesell said the last time there was an incident was in the 1980s when a couple of people were trapped on the elevator. Nobody died in that incident.

Mines that operate as tourist attractions in Colorado must designate someone to inspect the mines and the transportation systems daily, according to the state Division of Reclamation, Mining and Safety.

Mr Mikesell said he did not know the date of the last inspection. Records of the inspections were not immediately available online.

Governor Jared Polis sent state resources including a mine rescue team.

Cripple Creek is a town of about 1,100 in the Rocky Mountains southwest of Colorado Springs.

The mine opened in the 1800s and closed in 1961, but still operates tours. Its website describes a one-hour tour in which visitors descend 1,000 feet. It says they can see veins of gold in the rock and ride an underground tram.

A woman named Mollie Kathleen Gortner discovered the site of the mine in 1891 when she saw quartz laced with gold, according to the company’s website.