A month after a wildfire erupted at the edge of the Grand Canyon, US firefighters were struggling Monday to bring the blaze under control.

A lightning strike on July 4 -- Independence Day in the United States -- sparked a fire that spread rapidly on the northern rim of the canyon, a major draw for domestic and international tourists.

The Dragon Bravo Fire -- named after the Dragon rock formation near the conflagration's start -- was initially allowed to burn unabated as part of a natural cycle that thins vegetation and renews the landscape.

But a week later, strong winds whipped through Arizona and fanned the fire, pushing it through a major hotel, as well as the North Rim Visitor Center and some guest cabins.

A nearby water treatment plant was also damaged, venting chlorine gas into t

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