The Butternut Fire in Great Barrington is now 40% contained.

Operations are continuing with a smaller crew focused on observing, the Great Barrington Fire Department said on its Facebook page.

Firefighters expect the containment number to go up once they can get more accurate measurements of the burn area. The fire is controlled, and they have not lost any ground, firefighters said.

The perimeter around the fire is expected to be as much as 10 miles.

The entire fire area is dangerous, and people should stay clear. Fire officials will continue to monitor air quality, they said.