A wildfire burning in rugged terrain in a northern Arizona canyon grew significantly due to fires intentionally set by crews to rob the blaze of its natural forest fuels.

The fire's size reached 16 square miles by Saturday morning.

Officials say that crews have mostly completed burnout operations on the key northern flank of the Slide Fire and are preparing to make similar protection efforts on the fire's western end.

The burnout operations conducted Friday night by fire crews contributed to heavy smoke over Sedona and Flagstaff.

The wildfire grew by nearly 5 square miles since the latest report.

It's is burning around Oak Creek Canyon, a scenic recreation area along the highway between Sedona and Flagstaff.

No homes have been destroyed.

The fire is 5 percent contained.