CHARLOTTETOWN -- 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.

"Now our focus will be on trying to get a timeline on the events and activities of these four young men who came into Charlottetown, see what led to this tragedy and try to make some sense out of it," McGuigan said.

He said investigators were speaking to acquaintances and friends of the boys in order to get a better understanding of why there were in the building, which was vacant for years, when it caught fire.

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

The English Language School Board in P.E.I. said the two younger boys were students at Montague Intermediate School and Montague Regional High School. Statements of condolence were posted on the websites of both schools.

Seana Evans-Renaud, the principal of Montague Regional High School, said Irving was a Grade 10 student at her school.

"We're in total shock," Evans-Renaud said.

"He was a very well-liked young man at the school and his family and friends are devastated by the loss and we certainly are devastated at the school."

Evans-Renaud said Irving regularly attended school, was doing well in his classes and had a close circle of friends.

She said she had no idea why the boys were in the abandoned building.

"We're not sure why they were there and absolutely we would have questions," she said.

She said the school community was also concerned for a second, unidentified student who attends Montague Regional High School and was burned in the fire. He is being treated at a Halifax hospital and police are waiting to interview him.

Rev. John Lacey, a priest at St. Cuthbert's Roman Catholic Church in nearby St. Teresa, east of Charlottetown, said MacKinnon's family were parishioners at the church.

"After services yesterday everybody knew and was distraught," Lacey said. "As parents they can relate to the fear of losing a child."

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.

"There is a tremendous amount of debris that has to be sifted through," McGuigan 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.