Story highlights Official: The firefighters were part of a crew tasked with digging a fire line

"Evidently, their safety zone wasn't big enough, and the fire just overtook them," he says

A Facebook page is created in the memory of the firefighters

They were battling the Yarnell Hill fire, northwest of Phoenix, on Sunday

Nineteen firefighters were killed Sunday battling a blaze in Arizona, the state forestry division said.

The vast majority were from Prescott, said Wade Ward with the Prescott Fire Department.

State forestry official Art Morrison said the firefighters were members of a "hotshot" crew, tasked with digging a fire line and creating an escape route.

"In normal circumstances, when you're digging fire line, you make sure you have a good escape route, and you have a safety zone set up," Morrison said. "Evidently, their safety zone wasn't big enough, and the fire just overtook them."

The crew was fighting the Yarnell Hill fire, which broke out Friday northwest of Phoenix. The fire has grown to 1,000 acres, damaged three homes and forced the evacuations of residents in the communities of Peeples Valley and Yarnell, Morrison said.

Authorities believe lightning sparked the blaze.

Not including the 19 deaths reported in Arizona, there have been 43 firefighter fatalities reported so far in 2013, according to the U.S. Fire Administration. A total of 83 firefighters died last year while on duty.

People left their condolences and messages of support.

"Such a tragic loss. My heart aches for these brave souls, and for their families and friends," wrote one.

"I pray for the families and the town of Prescott. RIP," wrote another.