The fire is believed to be contained to the building, according to SDLP councillor Conor Galbraith who was at the scene.
“It doesn’t look like it could spread, with most of the fire located on the building’s roof, which appears to be caved in,” he told News NI.
A priest had been ordained there on Sunday afternoon, “just hours before the blaze,” he said.
He added that it was sad to see the fire in “such a historical part of our town”.
Galbraith’s party colleague, Colin McGrath, described the blaze as “difficult to watch”.
