33 photos: Wildfire forces Canadian city to evacuate  33 photos: Wildfire forces Canadian city to evacuate  Remains of a building stand in the neighborhood of Abasand in Fort McMurray on May 13.  33 photos: Wildfire forces Canadian city to evacuate  Burned trees dot the landscape in Fort McMurray on May 13.  33 photos: Wildfire forces Canadian city to evacuate  Canadian Prime Minister Justin Trudeau, left, and Fort McMurray Fire Chief Darby Allen look over the devastation during a visit to Fort McMurray on May 13.  33 photos: Wildfire forces Canadian city to evacuate  Charred remains of homes are seen in Fort McMurray on May 13.  33 photos: Wildfire forces Canadian city to evacuate  A police officer looks over a destroyed building in the Abasands neighborhood of Fort McMurray on Monday, May 9.  33 photos: Wildfire forces Canadian city to evacuate  Burned ground surrounds a sign welcoming visitors to Fort McMurray on May 9. The wildfire began Sunday, May 1, and had torched nearly 617,800 acres as of May 10, according to Alberta's Wildfire Management agency. The cause of the blaze was unclear.  33 photos: Wildfire forces Canadian city to evacuate  Remains of a burned-out house sit near intact homes in Fort McMurray on May 9.  33 photos: Wildfire forces Canadian city to evacuate  Smoke fills the air as a police officer checks vehicles at a roadblock along Highway 63 leading into Fort McMurray on Sunday, May 8.  33 photos: Wildfire forces Canadian city to evacuate  Rodney Howse gets water at a donation center on May 8. The center was established to help evacuees who were forced from their homes by the wildfire.  33 photos: Wildfire forces Canadian city to evacuate  A ball of flame rises behind abandoned vehicles on Highway 63 near Fort McMurray on Saturday, May 7.  33 photos: Wildfire forces Canadian city to evacuate  Foundations of homes are all that remain in parts of a residential neighborhood in Fort McMurray on May 7.  33 photos: Wildfire forces Canadian city to evacuate  Skeletons of patio furniture are seen on May 7.  33 photos: Wildfire forces Canadian city to evacuate  A helicopter helping with the Fort McMurray wildfire takes off from a staging base near Conklin, Alberta, on May 7.  33 photos: Wildfire forces Canadian city to evacuate  Remains of a home in Fort McMurray are seen on May 7.  33 photos: Wildfire forces Canadian city to evacuate  Charred vehicles sit in a heavily damaged residential neighborhood on May 7.  33 photos: Wildfire forces Canadian city to evacuate  Smoke and flames create a dramatic sunset near Fort McMurray on Friday, May 6.  33 photos: Wildfire forces Canadian city to evacuate  A huge plume of smoke from the wildfires rises over Fort McMurray in this aerial photograph taken on May 6.  33 photos: Wildfire forces Canadian city to evacuate  The remains of a swing sits in a residential neighborhood destroyed by the fire on May 6 in Fort McMurray.  33 photos: Wildfire forces Canadian city to evacuate  A plane drops fire retardant in Fort McMurray on May 6.  33 photos: Wildfire forces Canadian city to evacuate  A police helicopter lifts off through dust and smoke on May 6.  33 photos: Wildfire forces Canadian city to evacuate  Drivers wait for clearance to take firefighting supplies into town on Thursday, May 5, outside Fort McMurray.  33 photos: Wildfire forces Canadian city to evacuate  A member of the Royal Canadian Mounted Police surveys wildfire damage in Fort McMurray. The RCMP tweeted the photo on May 5.  33 photos: Wildfire forces Canadian city to evacuate  Tyra Abo sits on a cot at a makeshift evacuation center in Lac la Biche, Alberta, on May 5.  33 photos: Wildfire forces Canadian city to evacuate  A woman picks through donated clothing and goods at a makeshift evacuation center in Lac la Biche on May 5.  33 photos: Wildfire forces Canadian city to evacuate  The wildfire moves toward the town of Anzac on Wednesday, May 4.  33 photos: Wildfire forces Canadian city to evacuate  People camp out at a beach south of Fort McMurray on May 4.  33 photos: Wildfire forces Canadian city to evacuate  Evacuees watch the wildfire near Fort McMurray on May 4.  33 photos: Wildfire forces Canadian city to evacuate  Traffic is at a standstill on Highway 63 south as residents flee the wildfire on May 4.  33 photos: Wildfire forces Canadian city to evacuate  Robert Parker, left, and Matt Jones siphon gas from two snowmobiles for their truck on May 4.  33 photos: Wildfire forces Canadian city to evacuate  A helicopter flies past the wildfire in Fort McMurray on May 4.  33 photos: Wildfire forces Canadian city to evacuate  The wildfire rages through Fort McMurray on Tuesday, May 3.  33 photos: Wildfire forces Canadian city to evacuate  The wildfire burns through northern Alberta in this image released by NASA on May 3.
The mammoth fire devastating northern Alberta has now destroyed more than 877,000 acres -- more than four times the size of New York City.