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Containment vs. extinguished

Authorities will give daily updates about the percentage of containment that firefighters have reached. For example, when a blaze is 25% contained, it means crews have constructed a fire line around a quarter of its perimeter. A fire line is often a dirt trail built by firefighters using bulldozers or hand shovels that separates the blaze from the grass, brush and trees that feed the flames. In some cases, the lines will be reinforced by flame retardant dropped by aircraft. Fire lines can also include natural breaks such as roads, rocky areas or rivers. A fire line is also known as a fuel break.

When a fire is 100% contained, it doesn't necessarily mean that it is extinguished, but that it's controlled. “A fire isn't controlled until it is fully contained, and crews have extinguished flames and smoking/smoldering fuels, and removed unburnt fuels from about 300 feet inside the fire line perimeter,� the U.S. Forest Service said on its website. It could take crews several days to make sure hot spots have cooled down enough so there is little chance that flames will cross the fire boundary.

A fire is considered to be out when no hot spots and smoke are detected within the lines for at least 48 hours, the Forest Service said. However, large wildfires are often watched and patrolled until rain or snow eliminates all smoke.

Many wildfires burn for weeks or even months.

Evacuation warnings

If fire danger is imminent, authorities will issue orders to evacuate immediately. But officials can't force people to leave. Often, law enforcement will go door-to-door to let residents know that their lives are in peril.

Evacuation warnings are issued to let residents know that danger is mounting and they should be prepared to flee at a moment's notice.

When deciding to order people to leave, emergency managers consider a fire's behavior, the weather forecast and the amount of time it will take to flee, Russ Lane, fire operations chief for the Washington state Department of Natural Resources, .

They also consider the availability of shelters and the potential for harm or the loss of human life.

Occasionally, an order is given to shelter in place. This is typically done when there is either no time to escape an approaching fire or it would be more hazardous to evacuate than to remain in place, Lane said.

Mopping up

Crews stay on the scene for days and even weeks cleaning up an area that has burned. They cut down teetering trees, remove brush and other possible fuel that could reignite, clear roads, and generally make the scene as safe as possible.