YELLOWSTONE NATIONAL PARK, Wyo. -

The South Entrance to Yellowstone National Park is expected to remain closed this weekend because of a wildfire in Grand Teton.

The closure of U.S. 89/191/287 that leads into Yellowstone is forcing some Yellowstone visitors to take an hour-long detour.

Firefighters said Saturday the fire that was started by lightning on July 25 has scarred nearly 20 square miles and continues to spread. Several other fires burning in Yellowstone could require visitors in vehicles to be escorted.

Grand Teton and Yellowstone National Parks and Bridger Teton National Forest all have area closures in effect, but both national parks are still open to visitors.

With the highway blocked, visitors in Grand Teton who want to visit neighboring Yellowstone have to drive west into Idaho to access the West Entrance of Yellowstone.