Updated: 6:27 a.m. June 12

First discovered: 40 hours ago, 1:45 p.m. June 10

Initial location: San Bernardino County, Calif.

Fire type: Wildfire

Fire name: Ranch

Ranch Fire initially started 1:45 p.m. June 10 in San Bernardino County, Apple Valley.

After being active for 40 hours, it has burned 4,293 acres of federal land managed by the Bureau of Land Management, an increase of 88 acres since the last update. A fire crew of 373 has been working on site and, by Thursday morning, they managed to contain 40% of the fire. It is still undetermined what caused the fire. So far, managing this fire has required $1,400,000 in expenses.

Fire containment

Interpreting what 40% containment means

Containment indicates what percentage of the fire perimeter has been surrounded by a control line. In this case, it means that 40% of the wildfire is contained from spreading, while 60% is still uncontrolled.

Containment is part of a larger plan for managing a wildfire. It is normally expressed as a percentage and it refers to how much of the fire perimeter has been surrounded/enclosed by a control line that firefighters create. The containment percentage indicates a certain level of control, but it doesn’t always correlate to safety level. Also, it’s important to note that containment doesn’t mean a fire is out.

How is containment measured?

The incident’s central command constantly receives progress reports from firefighters on the ground. As the fireline is constructed, inspected or reinforced, mappers record those details to adjust the containment percentage. The percentage tells the public how much of the fire perimeter is believed to not go beyond the control lines.

Source: National Interagency Fire Center