The Army says a training explosion may have sparked a 6,500 acre wildfire on Fort Carson near Colorado Springs.

Fort Carson spokeswoman Karen Connelly said Wednesday the detonation of less than a quarter stick of the military explosive C-4 in a rock quarry may have caused the fire.

Connelly could not immediately provide details about the C-4 training.

About 90 firefighters from six agencies are working the blaze in a training area marked by ridges, rock outcroppings and quarries. It is 10 percent contained.

No structures have been destroyed and no injuries have been reported.

The fire started Tuesday. Connelly says it wasn't spreading Wednesday like it was during high winds a day before.