About 100 firefighters from Mexico were expected to arrive on Tuesday to help battle a deadly wildfire that has forced 20,000 people to flee and destroyed homes and other properties near Okanagan Lake in Western Canada, officials said. Hugh Murdoch of the British Columbia Wildfire Service said crews face a “monumental task” in steep terrain and hot conditions, with burning embers igniting new fires beyond the main perimeter and limiting opportunities for firefighters to attack the blaze directly. Summerland Mayor Doug Holmes warned on Monday that the town’s roughly 12,000 residents should not expect to return home soon. “We need to brace ourselves for what’s there or what’s not there,” Holmes said at a briefing, his voice breaking. The British Columbia Wildfire Service also warned of a high risk of new lightning-caused fires in the province’s central Interior and Okanagan region.