LOS ANGELES, Aug. 3 (Xinhua) -- Fueled by gusty winds and bone-dry timber, Arizona's Dragon Bravo Fire sweeping across the North Rim of the Grand Canyon National Park had grown to roughly 472 square km as of Sunday, according to the U.S. interagency website on wildfire.

The blaze, ignited by a July 4 lightning strike on the Walhalla Plateau inside the park, is only 12 percent contained as of Sunday despite the round-the-clock efforts of 1,214 firefighters supported by helicopters and large air tankers.

Over 900 people, 54 trail mules, and staff have been evacuated safely. Firefighters have been using graded forest roads, canyon walls and remnants of previous burns to contain the wildfire since mid-July.

Meteorologists expect monsoon moisture to drift over northern Arizona by mid-week, raising humidity and offering a chance of showers, the latest fire weather briefing said.

According to official records, the fire began as a smolder on July 4 before escalating dramatically over the following days. By July 10, authorities had evacuated 500 visitors as the threat intensified.

The situation became critical on July 12 when strong winds caused the fire to spread rapidly throughout the lodge district. The U.S. National Park Service confirmed the next day that the Grand Canyon Lodge, dating back to the 1920s, along with its stone dining room, dozens of pine-sided tourist cabins and several utility buildings, had been consumed in less than two hours.

By July 31, the fire had surpassed 400 square km, making it one of Arizona's ten largest wildfires in history.

Officials caution that full containment could still be weeks away, depending on weather, fuel moisture and the fire's behavior. ■