Update: Pass Fire in Alameda County is now fully contained
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Updated: 8:51 a.m. May 18
First discovered: 20 hours ago, 12:03 p.m. May 17
Initial location: Near Altamont Pass Road, Altamont, Alameda County, Calif.
Fire unit: Cal Fire Santa Clara Unit
Fire type: Wildfire
Fire name: Pass Fire
Pass Fire initially started 12:03 p.m. May 17 on Near Altamont Pass Road, Altamont in Alameda County, California.
After being active for 20 hours, it has burned 69 acres. By Monday morning, the fire crew successfully encircled the entire perimeter of the fire in control lines. The cause of it remains under investigation.
See live video from the area:
Https://cameras.alertcalifornia.org/?id=Axis-HighlandPeak2
Fire containment
What does 100% containment mean?
Note that full containment doesn't mean the fire is completely out. In this case, it means that the wildfire has been fully enclosed by a control line and it is now stopped from spreading. A fully contained wildfire may continue to burn within the containment perimeter but is not likely to spread.
However, there's a significant difference between containing and controlling a wildfire. After the fire is fully contained, the next step is to control it. Controlling a fire means ensuring that the fire can't spread or cross the containment line.
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
United Robots Sacramento
This story was originally published May 18, 2026 at 9:26 AM.