Update: Containment of Grand Fire in San Bernardino County grows to 50%

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Updated: 6:21 a.m. May 14

First discovered: 11 hours ago, 7:13 p.m. May 13

Initial location: Grand Avenue and Pleasant Hill Drive, Chino Hills, San Bernardino County, Calif.

Fire unit: Cal Fire San Bernardino Unit in Unified Command with Chino Valley Fire

Fire type: Wildfire

Fire name: Grand Fire

Grand Fire initially started 7:13 p.m. May 13 at Grand Avenue and Pleasant Hill Drive, Chino Hills in San Bernardino County, California.

Since its discovery 11 hours ago, it has burned 29.6 acres. 50% of the fire was brought under containment by a crew of 220 firefighters as of Thursday morning. Investigations into its cause are still ongoing.

The fire is fought by 20 engines, one water tender, three helicopters, two dozers and four hand crews. According to Cal Fire, "Numerous firefighting air tankers from throughout the State are flying fire suppression missions as conditions allow."

Fire containment

Interpreting what 50% containment means

Containment indicates what percentage of the fire perimeter has been surrounded by a control line. In this case, it means that 50% of the wildfire is contained from spreading, while 50% 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: Cal Fire

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This story was originally published May 14, 2026 at 6:42 AM.