There’s just one road running through Alaska’s Denali National Park, which sits in between Anchorage, to the south, and Fairbanks, to the park’s northeast. So when that road is blocked, it can be a problem. Like this weekend, when a massive mudslide covered part of the road, stranding visitors and park employees as crews worked to clear it, according to the Fairbanks Daily News-Miner

There were no injuries in the mudslide, and officials aren’t even sure when exactly it happened. But they said Sunday that mud was still sliding, creating a steady “ooze.” 

The slide likely began late Friday or early Saturday, when it was first discovered by park officials. The slide occurred at Mile 67 of the road, or about two thirds of the way down its complete length, and a mile beyond a visitor center.

Everyone that was stranded beyond Mile 67 was freed by Sunday evening, officials said, through a combination of air and ground. Some buses were able to traverse the portion of the road affected by the landslide, but it remained largely closed Monday as workers continued to clean up. 

Officials blamed the mudslide on soggy conditions in the area; this is the third mudslide that’s blocked the road just this year, and the worst by far.