An official with the Yavapai County Sheriff’s office says 19 firefighters have died while battling the Yarnell Hill Fire in a central Arizona community.

The Arizona Republic reported earlier that 19 firefighters were involved in a "serious incident."

A forestry department spokesman said the firefighters had been caught by the fire and were forced to deploy their fire shelters, tent-like structures meant to shield them from flames and heat.

The Yarnell Hill fire started Friday and picked up momentum Sunday as the region experienced high temperatures and windy conditions during a record-setting heatwave across the Southwestern United States.

One former resident tweeted: "Almost the entirety of my hometown's fire department has perished tonight. May they RIP and fire season be over posthaste."

The likely cause of the fire is lightning, according to a statement posted earlier Sunday on the Yarnell Fire Department website.

"The fire is currently 200 acres and growing," the early afternoon statement said. "The community should be on high alert particularly since we are expecting thunderstorms this afternoon."

The Yarnell Hill fire later grew to 2,000 acres, with at least 250 firefighters and four aircraft working to battle the blaze.

The region has called for federal help, and additional 150 firefighters and some aircraft are on their way.

The fire prompted evacuations Sunday of 50 homes in the Buckhorn, Model Creek and Double A Bar Ranch areas, which are about 135 kilometres northwest of Phoenix.

The Yarnell Hill fire also closed parts of state Route 89, the Arizona Department of Transportation announced.

The department did not have an estimate of how long the closure would last but advised drivers to use U.S. 93 or Interstate 17 as alternate routes.

Officials are expecting half of the town's 500 homes to be destroyed by the fire.

With files from The Associated Press