GLENWOOD SPRINGS, Colo. (AP) — About 20 people had to spend the night inside a highway tunnel after rain over an area burned by a wildfire once again triggered mudslides in western Colorado, authorities said Friday.

The people were caught with their vehicles Thursday night inside the tunnel along Interstate 70 in Glenwood Canyon for about nine hours until crews could carve out a path through the mud to reach them about 6:30 a.m. Friday, Garfield County Sheriff's Office spokesperson Walt Stowe said. The tunnel serves as a 24-hour operations center for the Colorado Department of Transportation, so it is relatively well-lit and has telephones, Stowe said. No injuries were reported.

Some vehicles remained stuck in the mud that slid on the open section of the highway, but it was not clear how many people may be in them, Stowe said. The Colorado Department of Transportation was working to reach them.

Glenwood Canyon has cliffs towering up to 2,000 feet (610 meters) above the Colorado River, making it prone to rockslides and mudslides. In recent weeks, rain over the area burned by a wildfire last summer has triggered frequent slides, resulting in closures of I-70, Colorado's main east-west highway. Those closures have mostly occurred before the storm moves in, to prevent people from being trapped.

On Thursday, the canyon had temporarily closed earlier in the day as one storm cell approached but had reopened by the time a second storm cell moved in, which led to the vehicles and their passengers getting trapped, Stowe said.