LYNN — The Fire Department reported that the fire, which started last Friday at 3:30 p.m., now stands at 427 acres and covers nearly 20 percent of the Lynn Woods Reservation, as of yesterday.

The fire lines within Lynn Woods remain intact and have not spread, but the fire continues to burn along the root system underground, according to the department’s most recent Facebook update. The breeze can cause small pockets of fire to flare up in the burn area.

The fire within the fire line is 20 percent contained, Public Information Officer Lt. Denis Ring clarified.

There were firefighting efforts throughout the weekend, but there were no firefighting activities yesterday, he said. The department is continuing to monitor the area.

The department reported that due to the ongoing drought and wind conditions, a Class 5 Red Flag fire danger was issued both Wednesday and yesterday. The current drought and wind conditions allow the fire to continue burning underground until the area receives significant rainfall.

The 2,200-acre reservation, which has entrances and parking areas on Pennybrook Road and Great Woods Road, is closed until further notice.

Hundreds of hallowed-out trees have fallen on paths and fire roads, which is one reason the reservation is closed to the public, the Fire Department said. Lynn Woods Park Ranger Dan Small and Urban Forestry Fellow Erica Holm are working together to evaluate trees that have not fallen, but are in a position to fall. Tree companies will soon enter the woods to clear the fire roads, allowing easier access to the area in case of an emergency.

“Right now the number one concern, outside of making sure the fire doesn’t spread, is the public safety,” Ring said.

The cause of the fire is unknown and still under investigation, the department said.

The department is providing ongoing updates on its Facebook page, City of Lynn Fire Department.