The wildfires burning at or near the Grand Canyon's North Rim are still raging as strong winds, high heat and low humidity persist.

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

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.

Authorities increased the size of the evacuation zone for the White Sage Fire north of the Grand Canyon on Friday morning.