A firefighting helicopter crew drops water on the Flat Fire, Aug. 24, 2023, in Central Oregon. /Oregon Department of Forestry

(NEW YORK) -- A veteran firefighter has died while battling one of multiple major wildfires burning in the West, authorities said on Monday.

The firefighter died on Sunday afternoon when he suffered a cardiac emergency while helping to fight the Bivens Creek Fire in southwest Montana, authorities, including Montana Gov. Greg Gianforte, confirmed.

"Rapid medical assistance was rendered from a line paramedic; however, resuscitation attempts were unsuccessful," the U.S. Forest Service said in a statement.

The firefighter, later identified as Ruben Gonzales Romero of Keizer, Oregon, was one of more than 740 firefighters battling the Bivens Creek Fire, which was burning out of control about 15 miles northwest of Virginia City, Mont., officials said.

The fire, which started on Aug. 13, was 0% contained on Monday after burning 2,242 acres.

In a statement, Gianforte described Romero as a "fallen hero" and expressed his condolences to his family and colleagues.

Romero, a firefighter for over 20 years, "brought significant experience and wisdom to the fire line and the people whom he worked," according to a statement from the Northern Rockies Complex Incident Management Team 6.

"We rest a little more comfortably knowing that he died doing what he loved," the statement said.

Elsewhere in the West, a fast-spreading wildfire in Northern California's wine country and a monstrous blaze in Central Oregon continued to threaten homes on Tuesday as firefighters battling the flames coped with extremely dry conditions and rugged terrain, authorities said.

Fire crews battling the Flat Fire in Central Oregon managed to increase containment of the fire overnight from 5% to 7%, according to the Oregon Department of Forestry. Firefighters fighting the Pickett Fire in Northern California's wine country managed to increase containment overnight to 17%, up from 13% on Monday, according to fire officials.

The Flat Fire, which started on Thursday near Sisters, Oregon, about 100 miles northeast of Eugene, has burned nearly 22,000 acres, according to the Deschutes County Sheriff's Office. The fire has destroyed at least 10 structures, including four homes, according to the sheriff's office. No injuries have been reported.

Nearly 3,000 homes remained threatened by Flat Fire, including some located within or near the perimeter of the blaze, according to the sheriff's office. Mandatory evacuations have been ordered for about 1,000 homes in the area.

The cause of the fire remains under investigation.

"We're starting to get a handle on this fire," Eric Perkins, an operations section chief on the fire, said in a video statement on Monday morning.

Despite minor growth on the north and west ends of the fire on Sunday night, Perkins said fire crews battling hot spots managed to keep the spread of the fire "relatively small."

More than 800 firefighters are battling the blaze amid Red Flag warnings and heat advisories, according to fire officials.

The Pickett Fire

Meanwhile, the Pickett Fire in Napa County, California, has prompted mandatory evacuation orders as firefighters continued to battle the blaze from the ground and air into Monday.

The Pickett Fire has burned 6,803 acres as of Monday morning, according to the latest update from the California Department of Forestry and Fire Protection (Cal Fire).

As of Monday morning, more than 600 structures remain threatened by the fire, but there were no reports of structures being destroyed or damaged, CalFire said.

More than 2,000 firefighters, including 10 helicopter crews, are fighting the fire, according to Cal Fire.

The Pickett Fire broke out around 3 p.m. local time on Thursday near the town of Calistoga, officials said. The cause of the blaze remains under investigation.

A marine layer moved into the area overnight, bringing "decent humidity" and helping firefighters keep the blaze from spreading, Cal Fire said in an update on Tuesday morning.

"Large fuels inside the perimeter continue to burn and smolder, which will cause visible smoke over the fire area today," Cal Fire further said. "Firefighters will continue containment efforts and mop up while working in steep, rugged terrain."

The fire is in the same region as the massive Glass Fire that scorched more than 11,000 acres in 2020.

"Leadership with prior experience in this rugged terrain, specifically from the 2020 Glass Fire, has been instrumental in guiding effective suppression efforts," CalFire said.

ABC News' Tristan Maglunog contributed to this report.

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