EMERY, Emery County — A search is underway in slot canyons near Goblin Valley State Park after flash flooding killed at least one person Monday. 

The Emery County Sheriff’s Office said in a news release that at least 21 people made it out of Little Wildhorse Canyon, but vehicles parked at trailheads in the area led searchers to believe there are hikers in the area still unaccounted for. As of Monday at 8 p.m., officials reported one fatality.

The search is being conducted by multiple agencies, including two helicopters from Classic Air in Moab and another from the Department of Public Safety, six ambulances, and search and rescue teams from four different counties, according to the Emery County Sheriff’s Office.

The flash flooding in slot canyons was caused by an “isolated thunderstorm” that crossed the San Rafael Swell Monday afternoon.

The National Weather Service in Salt Lake City tweeted that part of the storm, capable of “nickel-sized hail and strong winds,” crossed directly over Goblin Valley State Park.