ALTONA — As of Tuesday, crews had surrounded the Flat Rock forest fire and had it 75 percent contained.

The state Department of Environmental Conservation-led firefighters are now trying to improve the fire lines they’ve already cut and get control of the blaze, which has burned 531 acres since it started last Thursday.

State police aviation continued flying missions as needed to support the firefighting efforts.

More than 150,000 gallons of water have been dropped from the air.

There are 159 personnel on site from state and local agencies.

No structures are in danger, and no injuries have been reported.