* Fort McMurray in the heart of Canada’s oil sands region
* Commercial flights in and out of city halted, airport at risk
* Mandatory evacuation orders issued for communities to the south (Recasts updates with details on risk to airport, communities to the south)
By Rod Nickel
ANZAC, Alberta, May 4 (Reuters) - A massive wildfire that has forced all 88,000 people to flee the western Canadian oil city of Fort McMurray and burned down 1,600 structures is now threatening its airport and communities well south of the town, authorities said on Wednesday.
With a few neighborhoods already in ruins, worsening fire conditions Wednesday pushed walls of flames towards thousands of more homes in the northeastern Alberta town, in the heart of Canada’s oil sands region.
The winds also pushed flames toward the local airport, with webcam images showing black smoke engulfing the airport late on Wednesday evening. Officials confirmed that a hotel north of main terminal had caught fire.
As flames fanned south, officials also issued mandatory evacuation orders for the Anzac, Gregoire Lake Estates and Fort McMurray First Nation communities located about 50 km south of Fort McMurray.
Officials on the scene were forced to evacuate their make-shift emergency operations center for the second time in the span of less than a day as the flames spread south. Officials at the center said in a tweet that they were relocating to the town of Lac La Biche some 250 km south of Anzac.
Authorities said there had been no known casualties from the blaze itself, but fatalities were reported in at least one car crash among the evacuees. Thousands bunked down in arenas, hockey rinks and oil work camps, often short of fuel and food.
A huge cloud of black smoke was visible from well over 60 km (37 miles) away from the town. Traffic on the main road headed south had thinned to a trickle, however, after major jams on Tuesday when the evacuation order was given.
Stretches of the highway had been converted into make-shift campgrounds by people in cars, trucks and recreation vehicles, who were fleeing the inferno.
Firefighting crews have been unable to stop the wildfire, which has charred 18,500 acres (7,500 hectares) since it erupted on Sunday and exploded in ferocity.
“It is a possibility that we may lose a large portion of the town,” said Scott Long, an official with Alberta’s emergency management agency.
Major oil sands facilities were not in the path of the flames, but companies’ efforts to help employees and evacuees and protect pipelines led to a decline in production.
Images from the neighborhood of Beacon Hill in the city’s southeast showed rows of charred house foundations, their upper stories burned to the ground, and blankets of white ash within. Officials said 80 percent of houses in the neighborhood, nearly 600 in total, were destroyed.
The regional government said two other neighborhoods, Abasand and Waterways, had sustained “serious loss.” Alberta Premier Rachel Notley said a total of about 1,600 structures have been destroyed in Fort McMurray.
“There are certainly areas within the city that have not been burned, but this fire will look for them and it will find them and it will want to take them,” said Chief Darby Allen of the Fort McMurray fire department.
The province declared a state of emergency for what was shaping up to be Canada’s costliest natural disaster.
Prime Minister Justin Trudeau said the military can deploy air force planes to the stricken city as needed. Fort McMurray International Airport suspended all commercial flights.
It was the second major blaze in the oil sands region in a year. Last May, wildfires led to the evacuation of hundreds of workers from the region, and a 9 percent cut in Alberta’s oil sands output.
The wildfire’s knock-on effects on oil sands operations escalated on Wednesday, with five companies including Suncor Energy and Husky Energy reporting reduced production either because workers had been affected by the evacuations or because of precautionary pipeline shutdowns.
The impact on crude production volumes was not immediately clear, but Suncor said late on Wednesday it had shut its base plant operations - its largest oil sands mining site with a production capacity of 350,000 barrels of oil a day.
Its other thermal oil sands sites were operating at reduced levels.
Officials said very hot and dry conditions meant “extreme wildfire behavior” on all fronts around the fire.
The Canadian Red Cross said evacuees were calling the organization for help getting food and water.
A highway closure on Tuesday forced most evacuees to drive north, away from major cities. By Wednesday morning, the highway had reopened, but fuel had run out, stranding evacuees. Alberta’s transport department said it was escorting a fuel tanker north to help stranded drivers.
Twitter filled with offers of food, housing and animal care as worried evacuees asked officials and strangers alike about the status of their homes. Two babies were born at one evacuation center on Tuesday.
Wildfires were also raging in neighboring British Columbia on Wednesday, including a 9,000 hectare blaze in the province’s northeast that was threatening to spread across the border to Alberta, the B.C. Wildfire Service said.
Reporting by Nia Williams in Calgary, Julie Gordon in Vancouver, Leah Schnurr and David Ljunggren in Ottawa and Allison Martell, Ethan Lou, Andrea Hopkins, Fergal Smith, Amran Abocar and Euan Rocha in Toronto; Writing by Amran Abocar and Dan Whitcomb; Editing by Will Dunham, Mary Milliken and Tom Hogue