Nineteen firefighters were killed while fighting a central Arizona wildfire that was sparked by lightning Friday and extended quickly Sunday, threatening two rural mountain communities.

Nineteen firefighters were killed while fighting a central Arizona wildfire that was sparked by lightning Friday and extended quickly Sunday, threatening two rural mountain communities.

Homes were burned as the Yarnell Hill Fire approached Glenn Ilah, Arizona, Sunday.

Arizona Governor Jan Brewer asserted Sunday night that the 19 had passed away outside Prescott, Arizona. They were a highly specialized fire crew.

450 residents were evacuated, as high temperatures, low humidity and unpredictable winds made for "extremely bad conditions," according to local officials.

Bursts of air, steep slopes, and rocky conditions turned the firefighting to be a tough mission.

The authorities closed many roads and kept the north ones open to allow firefighting resources to enter the area.

About 250 to 300 firefighters were on the scene, and aircraft were grounded for the night.

It was estimated that the fire had burned at least 1,500 acres as of Sunday night.

American media reported that there are many puzzles still need to be interpreted regarding this disaster.