MONTAGUE, P.E.I. -- Police say their investigation into the deaths of three teenaged boys whose bodies were found after a weekend fire at an abandoned building in Charlottetown will now shift to finding out what led to the tragedy.

Deputy Chief Gary McGuigan of the Charlottetown Police Service said Monday the investigation is entering a new phase.

"The investigation will now focus on determining a timeline of events and activities on the four youths leading up to this tragic event," he said in a statement.

"Police have already conducted a number of interviews and will continue to interview and follow up with anyone who may have come in contact with the boys on that day to try to make some sense out of this terrible tragedy."

Police identified the three teenagers as: Joseph Reeves, 19, Brandon MacKinnon, 16, and Kenneth Irving, 15.

A Prince Edward Island school board said Monday that the two younger boys were students at Montague Regional High School and Montague Intermediate School.

The English Language School Board posted statements of condolence on the websites of the two schools.

The school board said another young person, who was injured in the fire, is also a student at Montague Regional High School.

His name has not been released and police have not been able to interview him yet at a Halifax hospital because of his injuries.

The cause of the fire has not yet been determined, but police said they do not suspect foul play. Bad weather and the condition of the building are hampering the investigation by fire officials, police said.

Montague Mayor Richard Collins said Sunday the deaths have stunned the community of 2,000 people, which is about 45 kilometres east of Charlottetown.

"My heart is broken as a father and grandfather, and the community is heartbroken," he said.

The fire started in a small, green building that had been vacant for years. Its windows and doors were boarded up but it has been home to a number of businesses in the past, including a used car dealership and a golf driving range.

The fire completely gutted the building and part of the roof collapsed.

Witnesses said the blaze started around 5:30 a.m. Saturday near the back of the building, and spread to the rest of the structure within a matter of minutes.