Cattle are seen near the flames of the Lodgepole Complex fire in Garfield County, Montana, July 21, 2017.
Cattle are seen near the flames of the Lodgepole Complex fire in Garfield County, Montana, July 21, 2017.

More than 600 firefighters in Montana battled on Tuesday to halt the spread of the biggest wildfire in the United States after it torched buildings, seared grasslands and drove scores of people from their homes.

The Lodgepole Complex fire was 20 percent contained after laying waste to 250,000 acres (101,171 hectares) of timber, brush and range land near the Missouri River, according to the National Interagency Coordination Center, which provides logistical support for wild land firefighting.

The fire has forced 50 people from their homes and destroyed 22 structures, it said.

The Lodgepole fire is the biggest of 45 active large fires burning across the United States, the National Interagency Fire Center said on its website.

Residents of sparsely populated Garfield County in eastern Montana, where the fire is burning, collected and transported relief supplies to people whose property has been damaged or destroyed.

Garfield County spokeswoman Anne Miller said in a telephone interview that donations of groceries, hay and money were pouring in to the tiny town of Jordan, Montana. Volunteers were mending fences, preparing food and gathering livestock.

"A house is considered a major loss, but the livelihood of most people here is the livestock, the pasture and grazing land," Miller said. "The majority of these people would have rather lost their homes than their grassland."

The Bureau of Land Management Montana/Dakotas said on Twitter that 611 firefighters from 34 states were striving to establish containment lines and protect structures from the Lodgepole fire.

Firefighters used bulldozers and harrows to plow fire breaks.

High temperatures, lack of rain and gusty winds have helped the fire spread.

"If conditions are right and the lines hold, crews will take the opportunity to start working from the fire's edge to cool more of the interior," an interagency statement on the fire information website InciWeb said.

The Lodgepole Complex started on July 19 as four fires after a lightning storm. The fires converged on July 21.