NORTHERN CALIFORNIA -- The American Fire burning in Placer County has grown to more than 7,000 acres as of today.

That is an increase in almost 2,000 acres since Thursday.

And containment has fallen since yesterday -- to 31 percent -- because of dense fuels and some very steep terrain. Tahoe National Forest Spokesman Jerry Westphal expects a continued spread.

1,200 personnel are now on hand, as are eight helicopters.

"All the movement is toward the northeast," Westphal said.

One mining structure has been burned and there have been two minor injuries.

But there have been no evacuations at this time, Westphal said.

Smoke is still a concern. Air quality is unhealthy for sensitive groups.

See photos of the American Fire.