Containment measures the percentage of a fire's perimeter that firefighters have under control. Parts of the fire's interior may still be burning.

The Palisades and Eaton fires, two of the deadliest and most destructive wildfires in California history, reached 100 percent containment more than three weeks after they began.

NBC News reports that the California Department of Forestry and Fire Protection declared the Palisades and Eaton Fires as 100% contained on Friday. Both fires broke out on Jan. 7 and combined burned more than 37,000 acres across Los Angeles County.

Eaton Fire initially started 6:18 p.m. Jan. 7 in Los Angeles County. Since its discovery 16 days ago, it has burned 14,021 acres. A fire crew of 1,837 has been working on site and, as of Thursday morning, they managed to contain 95% of the fire. However, investigations into the cause are ongoing.