@YosemiteNPS/Twitter(MARIPOSA COUNTY, Calif.) — Firefighters are struggling to contain a deadly wildfire that more than doubled in size on Monday, charring nearly 9,300 acres of land near Yosemite National Park in California’s Sierra Nevada Mountains.The so-called Ferguson Fire, burning in Mariposa County about 70 miles northwest of Fresno, increased to 9,266 acres by Monday evening, up from about 4,000 acres on the previous day, fire officials said.The fire, which ignited Friday, was only about 2 percent contained by Monday at 7 p.m. local time as crews grappled with the area’s steep mountain terrain and extreme temperatures that made it difficult to slow the fire’s spread.“Due to continued hot and dry conditions over the next five days we urge you to be vigilant with your safety,” Cal Fire said in a statement Monday. “With decreased visibility due to the smoke please stay cautious and be aware while driving in and around the fire area.”At least 1,486 fire personnel were deployed in an effort to stop the flames from reaching more than 100 homes and other structures that are threatened, fire officials said.Braden Varney, a bulldozer operator with Cal Fire’s Madera-Mariposa-Merced Uni, died while battling the fire on Saturday when his bulldozer reportedly rolled over. Crews retrieved his body on Monday as intense flames had hampered workers from getting to the scene earlier.The cause of the fire is under investigation.The Ferguson Fire is one of at least 34 large wildfires burning across the American West, where temperatures have reached triple digits in some areas this week.Nearby Yosemite National Park, a go-to tourist destination for camping and hiking, remains open to visitors, but officials said poor air conditions could force visitors to limit strenuous outdoor activities.“Visibility and air quality in Yosemite continue to be affected by smoke from the #FergusonFire,” park officials said in a tweet late Monday. “Smoke may be heavy at times; be prepared to limit any strenuous outdoor activity during the periods of high concentration.”State Route 140, a key route into the park, was partially shut down over weekend, forcing motorist to find alternate ways inside.Several nearby areas were placed under mandatory evacuation, including Clearing House, Mariposa Pines, Cedar Lodge/Savage’s Trading Post and Sweetwater Ridge, officials said Monday, adding that other nearby residents should be prepared to evacuate at anytime.Copyright © 2018, ABC Radio. All rights reserved.