Court hearings Thursday for three boys charged with setting a massive fire in a vacant Sanford mill last month were continued until October to allow the three juveniles to be evaluated further.

The three, who are charged with arson, are currently under house arrest. Two are living with their parents and the third is with his grandparents. All three boys denied responsibility for the fire after they were charged with felony arson three days after the fire.

The three – two 13-year-olds and a 12-year-old – are from Sanford. They were originally held at Long Creek Youth Development Center in South Portland after their arrests and released to their families on July 5.

Tanya Pierson, an assistant York County District Attorney, said the boys and their families are receiving intensive services, including counseling and therapy.

They will continue to be held under house arrest until their juvenile corrections officers determine if they can be released for part of the day and follow a curfew, she said. The house arrest rules bar them from having friends over, but will allow them to attend school when classes resume, Pierson said.

The next court dates for the three will be in October – two on Oct. 12 and the third on Oct. 26.

In the meantime, prosecutors and the three boys’ lawyers will discuss a possible plea agreement to avoid a trial, Pierson said. She noted that the chief objective in juvenile matters is rehabilitation, and punishment is last on the list of goals.

Family members who attended the brief scheduling hearing Thursday morning at Biddeford District Court declined comment.

The fire, which smoldered for days, was the largest mill fire Sanford firefighters have ever battled, rivaling a 1984 New Year’s Eve fire in Sanford that destroyed several businesses and apartment buildings on Washington Street. About 100 firefighters from 20 departments fought the June fire and many remained on the scene for days, dousing hot spots that flared up.

No one was injured in the fire.

Authorities have not said how they identified the boys as suspects in the fire or commented on a motive.

Pierson said a brief affidavit was filed by Sanford police, but Thursday afternoon, District Court Judge Daniel Driscoll said he would not release it or any other additional information on the three. Because arson is a Class A crime, considered among the most serious felonies in Maine’s criminal system, the proceedings involving the three boys are public, but the Press Herald is not releasing their names until more details are released about how the fire started are released.

Pierson said an investigation by the state Fire Marshal’s Office is not yet complete.

According to the fire marshal’s 2015 annual report, the most recent year for which statistics are available, investigators catalogued 312 instances of juveniles setting fires.

About a third of them – 102 incidents – were structural fires that caused nearly $3.68 million in damage.

On average between 2010 and 2015, the most recent years for which statistics were available, juveniles set 239 fires annually.