Fort McMurray, Alberta: The houses had literally melted. Hundreds of them. Two-storey, plastic-sided homes were down to concrete slabs with stairs leading nowhere. Some iron railings survived, but even they sagged, a stark reminder of just how hot this fire had burned.

There were no people for blocks across the destroyed Beacon Hill neighbourhood on Friday morning. The city’s 88,000 residents had been evacuated three days earlier as the walls of flame closed in. An area the size of several football fields looked like a post-apocalyptic movie set.

Even the usual signs of interrupted life were scarce: Furniture and appliances had burned up, with the hard metal pieces of barbecue grills, some particularly sturdy lawn furniture and the skeletons of curbside mailboxes remaining.

Late on Thursday, a convoy of trucks rolled into the scorch zone ferrying diesel fuel, aviation fuel, mobile kitchens and other essentials to the emergency crews fighting the fire, which has already burned 250,000 acres – an area bigger than Dallas. After a few hours of rough sleep in our rented SUV, a colleague from Getty Images and I set out at around 7:30 am in the thick haze to see what the flames had wrought.

It was clear that the fire had whipped through very quickly and somewhat erratically. People did not have time to take valuables, and there were clear signs of what I would classify as panicked retreat. On the road leading into the city, at least a dozen cars had been abandoned in the median – I imagined people trying to drive across the divided highway, getting stuck and then just climbing into someone else’s car.

But the blaze seemed to have been selective, burning one area to the ground and, depending on how the wind was blowing at that particular moment, sparing another. The edges of the city, where the forest abuts the residential areas, were all but gone. Yet on one empty lot sprinkled with ash, a hot-pink bicycle with training wheels lay on the sidewalk’s edge, seemingly untouched and ready to ride.

On Fort McMurray’s main drag, Franklin Avenue, the storefronts stood largely unscathed: Podollan Inns and other B-minus motels. An Esso gas station. A few bars dotting either side of the street. Traffic lights flashed green and red, although there were scarcely any drivers to go and stop. Canadian flags with their bright red maple leafs fluttered from utility poles, neither singed nor tinged with soot.

The fire was still raging, but a few miles from the city. It remained too big and fast for firefighters to really engage. Occasionally, we would see a helicopter or plane in the distance, presumably dropping water on the flames.

I’ve covered the aftermath of natural disasters like the 2004 tsunami in Indonesia and the earthquake in Pakistan the following year. Those were acts of nature that ended quickly. This is different, because it’s a continuing threat. The fire is still burning out of control, and no one really knows the direction it will take.

No one knows, either, when Fort McMurray residents will be allowed into the city to check on their homes, never mind move back.

Because this fire is so big and not being fought at this point in a way that one could photograph, I am focused more on its aftermath and how it affected the population.

I’m documenting the trees now bereft of their branches. The seared hulls of washers and dryers from what must have been a laundromat. The aluminum car parts that had become silvery puddles. The homes, all those homes, that used to have families and now do not have walls.

Driving the 235 miles up from Edmonton had taken about six hours. We hit the first police roadblock, 11 miles south of Fort McMurray, at about 8 pm on Thursday, and found a line of 18-wheelers laden with supplies. Drivers stood outside their trucks, slurping coffee from thermoses or stuffing hands into jean pockets. They seemed unflustered by the wait; they were just eager to get their loads to people to help them do their jobs.

Slowly the convoy began to move, and we joined it. We ended up north of downtown, in MacDonald Island Park, which had become a staging area. It was cold overnight, even in our sleeping bags.

Early on Friday, there was a lot of smoke and ash in the air, more than there had been overnight. But by noon, the sun was shining and the air was much clearer; the thermometer topped 60 degrees Fahrenheit. There was an eerie silence.

I did not bring special gear, just heavy hiking boots and warm clothes for nighttime. We have two cases of bottled water and jerrycans full of gasoline. We’re eating crackers, cheese, cola – all the unhealthy stuff. We’ve got a basic medical kit and, of course, a power converter, the kind that plugs into the car’s cigarette lighter, to keep the computer, phone and cameras humming.