WHITBY -- The long weekend saw firefighters battling a fire at Whitby's old Purina pet food plant all day Sunday.

Whitby Fire Department was called out at 6 a.m. Sunday for a smokey blaze at 280 Hopkins Street, just south of Dundas Street.  The fire was in a brick weigh house, approximately 10 by 20 metres in size, at the entrance to the property.

According to Platoon Chief Peter Heron, the fire kept 18 firefighters with four trucks busy all day. By 7 p.m. it was all over and the building, which was deemed unsafe, had been destroyed.

Whitby Fire Prevention Officer Terry Von Zuben said the preliminary damage estimate was $300,000.

The building was vacant and the power had been turned off, and Mr. Von Zuben said the cause is being treated as suspicious.  Durham Regional Police are investigating.

No one was injured in the fire.

In the wake of the incident, Whitby fire officials are asking owners of vacant buildings to make sure that they're secured against unauthorized access.