FORT MCMURRAY, Alta. - A wildfire has devastated the community of Fort McMurray. Here is a timeline of events:

Sunday — A fire starts in a remote part of forest southwest of Fort McMurray. Investigators don't know how it started, but have noted that most spring wildfires are caused by people. A dry, warm spring and trees that are still greening make for lots of fuel. Fire spotted by helicopter fire patrol. Helicopter begins working the fire immediately. First air tanker arrives 45 minutes later, then three others arrived from Lac la Biche, Peace River and Whitecourt. Two tankers stayed the night in Fort McMurray to be ready to go the next morning

Sunday 7:08 p.m. — The Alberta Emergency Alert system warns people who live in Fort McMurray's Gregoire neighbourhood to prepare to evacuate on short notice.

Sunday 10:33 p.m. — A state of local emergency is declared and a mandatory evacuation order is issued for Gregoire as well as for Centennial Trailer Park south of Airport Road.

Monday 3:37 a.m. — Mandatory evacuation notice for Gregoire is reduced to what is called a voluntary, shelter-in-place notice and people are allowed to return. The 700 residents from the trailer park as well as another neighbourhood, Prairie Creek, remain out of their homes.

Monday during the day — Aircraft drop fire retardant and ground crews work to protect homes. The fire is one-square-kilometre in size. "We are hopeful that we can stop this fire before it gets into town," says Wood Buffalo fire Chief Darby Allen. The fire is within one kilometre of homes at points, but the wind is pushing it away from the city. The evacuation order for Prairie Creek is lifted in the evening. "All things considered, it is looking good,'' says Mayor Melissa Blake. "But I have that worry if the wind changes direction we are still in a perilous situation."

Overnight Monday and Tuesday morning — The fire grows to 26 square kilometres, but is still moving away from the city. Life in Fort McMurray seems relatively normal. Allen warns people not to let their guard down.

Tuesday 10:30 a.m. — A change in normal atmospheric conditions, called an inversion, breaks. This, coupled with temperatures in the range of 30 C, low humidity and shifting winds, causes the fire to explode.

Tuesday 2:25 p.m. — Flames are heading toward the city and huge plumes of smoke are visible. Residents of three south-side neighbourhoods are ordered from their homes. There's shock at how quickly the situation has deteriorated: "When I got in the shower earlier today the sky was blue. When I got out, the sky was black," says resident Sandra Hickey.

Tuesday 3:45 p.m. — There's chaos on the city's south side as people flee towering walls of orange flame that are charging into neighbourhoods. Residents are told to head either north or south, depending on their location, on the one highway through town. The evacuated trailer park is on fire. Flames are advancing towards a Super8 motel and a gas station. "People are panicking. It's gridlock on the roads," says Carina Van Heerde, a reporter with radio station KAOS.

Tuesday 4 p.m. — Parts of the downtown are put under an evacuation order.

Tuesday 5:22 p.m. — Alberta Premier Rachel Notley says the province is doing all it can to ensure everyone's safety. Scott Long of Alberta Emergency Management says the flames have burned a number of structures, but he can't say how many.

Tuesday 6:31 p.m. — All of Fort McMurray is placed under a mandatory evacuation order.

Tuesday evening — Pictures and video on social media depict a hellish scene of fountains of flame. Flames are jumping roads and burning debris is pitched into the paths of cars. Frantic residents line up bumper to bumper as they scramble to find their way through the thick grey haze.

Tuesday 10:20 p.m. — Emergency officials say whole neighbourhoods have been destroyed. Still, there are no reports of serious injuries. Crews are trying to maintain crucial infrastructure, including the only bridge across the Athabasca River and Highway 63.

Wednesday morning — Highway 63 leading south is "organized confusion." Cars are strung along ditches and police are running jerry cans of gasoline to drivers who have run out. To the north of the city, thousands have taken refuge in oilsands work camps.

Wednesday 10:23 a.m. — Notley says the wildfire has destroyed roughly 1,600 structures in the city.

Wednesday 3:57 p.m. — The Alberta government declares a provincial state of emergency so it can take control of the response.

Wednesday 10:03 p.m. — A small community to the south of the city, Anzac, is put under an evacuation order. Some evacuated residents have to pack up and move again.

Thursday noon — The fire has ballooned to more than 850 square kilometres. There's a plan to airlift evacuees who were cut off when they fled north.

News from © The Canadian Press, 2016