A wildfire burning in Grand Canyon National Park triggered a chlorine gas leak Friday afternoon after flames reached a water treatment facility.

Authorities maintained the evacuation zones for the White Sage Fire north of the Grand Canyon as the fire grew expectantly.

Visitors and staff at two national parks in the U.S. West have been evacuted because of wildfires. Officials at Black Canyon of the Gunnison National Park in Colorado say the park closed Thursday morning after lightning sparked blazes on both rims.

A 63-year-old woman was found a quarter mile away from her vehicle. The investigation indicated she was returning to the trailhead when she collapsed.