Four firefighters from Pembroke are heading to Slave Lake, Alta. to help fight intense forest fires there.

A total of 85 firefighters from Ontario are leaving for Alberta on Tuesday.

Thousands were forced to flee the small northern Alberta town over the weekend after high winds pushed a raging wildfire into the community.

The fire has ruined many prominent buildings, including the town hall, the local library and the main shopping mall.

The mayor says about half the homes in the hardest-hit residential area have also been damaged or destroyed.

However, officials say the full extent of the devastation won't be known until the fire can be brought under control.

Local authorities first began battling two separate fires near Slave Lake on Saturday, to the east and south of the town. It was initially believed that the fires could be brought under control.

The next day, officials called for an evacuation of Slave Lake after a raging fire ripped through the town.

Slave Lake, which has a population of 7,000 people, is located about 250 kilometres north of Edmonton.