Officers have blocked the road at Hillside Street to stop people from entering the Blue Hills Reservation by Houghton’s Pond where the fire appears to be. About 100 firefighters battled what started as a one-to-two-acre fire about a half-mile into the woods near Houghton’s pond. Most left by dark last night for a small crew to monitor.

The brush fire was about 40 acres wide and only 10 percent contained Monday night, according to a spokesperson for the Massachusetts Department of Fire Services.

Hillside Street in the Blue Hills Reservation is closed due to the brush fire and extends from the three-way stop sign at Blue Hill River Road to the intersection of Unquity Road and Chickatawbut Road, which is just beyond the State Police barracks. The Houghton’s Pond main lot, along with Lots B and C, are closed as well.