Elon Musk’s Boring Company has reportedly stopped work on a tunnel it’s been digging to the Las Vegas airport after a worker sustained a “crushing injury” late Wednesday night, according to Fortune. Nevada’s Occupational Safety and Health Administration (OSHA) has opened an investigation.

The Clark County Fire Department received a call at 10:12 p.m. local time on Wednesday and dispatched an 18-person rescue crew to the site. It’s unclear exactly what happened to the worker, but the individual was lifted out of the job site by the local fire department, which used an on-site crane. The fire department told Fortune the worker is “reported to be stable.”

The Boring Company has spent the last few years digging tunnels that connect the Las Vegas Convention Center with a small number of nearby hotel casinos. The underground transportation system has provided over 3 million rides across the 3.5 miles of tunnels currently in service. The company has much larger ambitions of connecting nearly all of Las Vegas by underground tunnels, including the airport.

But dozens of workers have been injured during construction of these tunnels, and even the company’s former safety manager for the Las Vegas project has publicly voiced concerns about the dangers faced at these sites.