BIG SUR (CBS SF) – The Soberanes Fire in Monterey County is now at 51,000 acres (79.6 square miles) and is 27 percent contained, Cal Fire officials reported Thursday morning.

The massive brush fire, caused by an abandoned campfire, broke out the morning of July 22.

READ MORE: Reports of Breakthrough COVID-19 Infections Cause Concern

The rugged terrain in the area has made it difficult for the more than 5,000 firefighters working to extinguish the blaze.

The fire started in the area of Soberanes Creek in Garrapata State Park, Cal Fire officials said.

READ MORE: San Mateo Schools Prepare For COVID Outbreaks During Upcoming Academic Year

Investigators have estimated the fire won’t be fully contained until the end of the month.

As of Thursday, the Soberanes fire is the largest wildfire burning in California.

MORE NEWS: COVID: San Jose Latest To Require Vaccination Or Weekly Testing For City Employees

TM and © Copyright 2016 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2016 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. Bay City News Service contributed to this report.