Firefighters battling the largest wildfire in Texas history face increasingly difficult weather conditions on Saturday.

The Smokehouse Creek Fire that began Monday has killed at least two people, left a charred landscape of scorched prairie, dead cattle and destroyed as many as 500 structures, including burned-out homes, in the Texas Panhandle.

The National Weather Service issued a red flag warning for the entire Panhandle from late Saturday morning through midnight Sunday after rain and snow on Thursday allowed firefighters to contain a portion of the fire.

Signs warning travelers of the critical fire danger are in place along Interstate 40 leading into Amarillo.

Winds gusts of up to 45 miles per hour (72 kilometres per hour) are expected Saturday with humidity below 10% and a high temperature of 75 degrees F (24 degrees C).

鈥淣ew fires could also potentially start 鈥� the relative humidities are very low, the wind gusts are high and so it doesn鈥檛 take much, all there needs to be is a spark鈥� to ignite another fire, said meteorologist William Churchill with the National Weather Prediction Center.

The fire, which has merged with another fire and crossed the state line into western Oklahoma, has burned more than 1,700 square miles (4,400 square kilometers) and was 15% contained, the Texas A&M Forest Service said Friday.

The cause of the fire remains under investigation, although strong winds, dry grass and unseasonably warm weather fed the flames.

鈥淓verybody needs to understand that we face enormous potential fire dangers as we head into this weekend,鈥� Republican Gov. Greg Abbott said Friday after touring the area. 鈥淣o one can let down their guard. Everyone must remain very vigilant.鈥�

Two women were confirmed killed by the fires this week. But with flames still menacing a wide area, authorities haven鈥檛 yet thoroughly searched for victims or tallied homes and other structures damaged or destroyed.

Two firefighters were injured battling the flames in Oklahoma. One suffered a heat-related injury and the other was injured when the brush pumper he was riding in struck a tanker truck as the two were heading to fight the fire near Gage.

Both firefighters are expected to recover.

Texas Agriculture Commissioner Sid Miller said individual ranchers could suffer devastating losses due to the fires, but predicted the overall impact on the Texas cattle industry and consumer beef prices would be minimal.

The number of dead cattle was not known, but Miller and local ranchers estimate the total will be in the thousands.

Associated Press journalists Ty O鈥橬eil in Stinnett, Texas, Jamie Stengle in Dallas, and Ken Miller in Oklahoma City contributed.

Sean Murphy And Jim Vertuno, The Associated Press