* Fire conditions extreme, with low humidity, gusting winds
* Emergency tankers helping refuel stranded evacuees onhighway (Adds fire has grown 10 times in size, government airliftingevacuees)
By Rod Nickel
LAC LA BICHE, Alberta, May 5 (Reuters) - A catastrophicwildfire that has forced all 88,000 residents to flee FortMcMurray in Alberta, Canada exploded tenfold in size onThursday, cutting off evacuees in camps and shelters north ofthe city.
The out-of-control blaze has burned down entireneighborhoods of Fort McMurray in Canada's energy heartland andforced a precautionary shutdown of some oil production, drivingup global oil prices.
Three days after the residents were ordered to leave FortMcMurray, firefighters were still battling to protect homes,businesses and other structures from the flames. More than 1,600structures, including hundreds of homes, have been destroyed.
Although the cause of the fire was unknown, officials saidtinder-dry brush, low humidity and hot, gusting winds left crewsunable to stop the flames.
The blaze, which erupted on Sunday, grew from 18,500 acres(7,500 hectares) on Wednesday to some 210,000 acres (85,000hectares) on Thursday, an area roughly 10 times the size ofManhattan.
"What people in that region have gone through in the lastcouple of days is literally hell on earth," Rona Ambrose, leaderof the opposition Conservative Party and an Albertan, fightingback tears as she addressed the Canadian Parliament in Ottawa.
Fire has intermittently blocked the only route south towardmajor cities, so thousands of evacuees fled north toward oilcamps and a few small settlements but found themselves with noroad route out.
Some 20,000 people were stranded in oil camps, makeshiftshelters and on roadsides north of the city where the flames cut them off from Fort McMurray. Most of Alberta's oil sandsfacilities are north of the city and not in the path of theflames.
Evacuee Jason Blair said he only had enough time to grab afew belongings before driving north to a Canadian NaturalResources Ltd facility.
"For some reason I really wanted my son's first pair ofshoes," he told CBC television.
An airlift of evacuees began from oil facility airstrips onThursday.
Canadian Natural Resources said it airlifted about 2,600people over the last 24 hours to Edmonton and Calgary, includingits own workers, to make room for more evacuees.
Frightened evacuees north of the city took to Twitter,asking when they would be able to drive south and whether areasto the north were safe.
"We're just sitting in a camp praying to get out!! Give usanswers!!! Please," Twitter user @jennimac780 told the regionalgovernment.
"We haven't forgotten about you and you're safe," thegovernment said on Twitter.
The winds gave the city a brief reprieve on Thursday bydriving the fire to the southeast, away from populated areas.But officials warned that the unpredictable weather could shiftagain.
The winds pushed flames toward the local airport, whichsuffered minor damage and was open for limited non-commercialoperations, officials said.
A makeshift emergency operations center at the airport wasevacuated for the second time in less than a day.
At least 640,000 barrels per day of crude output is offline,according to Reuters calculations, roughly 16 percent ofCanada's crude production. The outage is expected to climb asmajor players in the region cut production.
The forecast has called for cooler temperatures and apossibility of rain, offering hope that controlling the blazecould become easier. Meteorologists put the chance of rain at 30percent on Thursday.
Authorities said there had been no known casualties from theblaze itself, but fatalities were reported in at least onevehicle crash along the evacuation route.
(Reporting by Ethan Lou, Andrea Hopkins, Allison Martell andAmran Abocar in Toronto, Nia Williams in Calgary and Liz Hamptonin Edmonton; Writing by Andrea Hopkins and Dan Whitcomb; Editingby Jeffrey Benkoe and Cynthia Osterman)
