Update: Border 6 Fire spreads to 40 acres in San Diego County, remains 10% contained

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Updated: 11:58 a.m. June 2

First discovered: 22 hours ago, 1:54 p.m. June 1

Initial location: Tijuana River, Marron Valley, San Diego County, Calif.

Fire unit: Cal Fire San Diego Unit

Fire type: Wildfire

Fire name: Border 6 Fire

Border 6 Fire initially started 1:54 p.m. June 1 in Tijuana River, Marron Valley in San Diego County, California.

After being active for 22 hours, it has burned 40 acres, an increase of 20 acres since the last update. By Tuesday noon, the fire crew managed to contain 10% of the wildfire. The blaze's cause remains under investigation.

Fire containment

What does 10% containment mean?

The percentage indicates how much of the fire perimeter has been surrounded by a control line. In this case, it means that 10% of the wildfire is halted from spreading, while 90% 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 June 2, 2026 at 10:29 AM.