Strong winds have spread flames and led to a town’s evacuation while planes dropped fire retardant over parts of Texas in an attempt to stop the largest wildfire in the US state’s history.

As of Sunday afternoon, the Smokehouse Creek fire was 15% contained and two other fires were at least 60% contained.

Authorities have not said what ignited the fires, but strong winds, dry grass and unseasonably warm temperatures fed the blazes.

A cluster of fires have burned across more than 1,900 square miles in rural areas surrounding Amarillo. The largest blaze, Smokehouse Creek, accounting for nearly 1,700 square miles, spilled into neighbouring Oklahoma.

US homeland security secretary Alejandro Mayorkas said the federal government has devoted funds, equipment and personnel to assist with battling the fires, but warned more extreme weather could be coming.

“More than a million acres have burned. And we are in winter, and this is the largest fire in Texas history,” Mr Mayorkas said during a CNN interview.

“We, as a country and as a world, have to be ready for the increasing effects of extreme weather caused by climate change. It’s a remarkable phenomenon, and it will manifest itself in the days to come, and we have to prepare for it now.”

The National Weather Service warned of an elevated fire risk throughout Monday in the area due to winds of 15-20mph.

Strong winds spread the flames, prompting an evacuation order to be issued in Sanford, a Texas town of a little more than 100 residents, according to a post by the Amarillo office of the National Weather Service on X, formerly Twitter.

As firefighters fought the unprecedented wildfires, humanitarian organisations pivoted to victims who have lost their homes and livelihoods. Residents began clearing affected property on Saturday and by Sunday the extent of the loss began mounting.

“We already know that a large group of people are uninsured who lost their homes. So without monetary assistance, it’s going to be very hard for them to start back over,” said Julie Winters, executive director for Hutchinson County United Way.

A steady outpouring of donated clothing, water and hot meals quickly overwhelmed one community in the affected area.

The city of Borger, Texas, urged people in a social media post to redirect donation efforts from food and water to clean-up supplies including shovels, rakes, gloves and rubbish bags.