By The Associated Press

Firefighters are making progress in containing a wildfire near Superior that has charred more than 2,600 acres.

Tonto National Forest spokeswoman Debbie Cress said Wednesday the fire is 40 percent contained and isn't threatening any structures.

The fire, which is burning about 3 miles south of Superior, began Sunday in the Tonto National Forest northwest of Phoenix.

Authorities say the cause is under investigation.

The blaze has been named the "257 Fire," for Forest Road 257, which is where the fire started in a wash.

Cress said about 330 firefighters were laying fire lines to stop the blaze from moving north or eastward. She said the fire's size will like increase somewhat as crews conduct burn operations.