The cause of a fire that has shuttered Victoria Park Arena for months now has been revealed, but the fate of the city-owned rink has yet to be determined.

Spontaneous combustion is to blame for starting the May 27 fire on the roof of the 50-year-old building, according to Brampton fire officials.

Fire investigators determined there was “spontaneous heating” inside a cotton mop head that had been left on the roof, hanging over the edge of a mop bucket. The roof mop spontaneously combusted, officials confirmed.

It happened on the flat part of the roof, which was under construction at the time.

The outdoor fields remained open, but the building has been closed ever since.

Damage estimates and structural engineering inspections have not yet been completed. The damage has been described by the city as “significant,” and includes damage to roof trusses and the roof deck, rink boards and glass, perimeter walls, some building systems and contents.

The city’s insurance company is still considering the extent of the damage to the building and its contents, and looking at how much it will cost to repair or replace it, according to city spokesperson Natalie Stogdill.

A report, with options for the future of the arena, is expected to be complete in the next two months and presented to council for a decision.

Brampton firefighters were called around 7:30 p.m. to the single-ice-pad arena building located on Victoria Crescent in the area of Bramalea Road and Avondale Boulevard. A citizen reported the fire and no injuries were reported.