Dark, uniformed figures wearing helmets and gas masks moved through the smoke as if in slow motion, visible one moment, receding into the vapours which covered the crash site the next.
Hoses still squirted great fountains of water on the smouldering wreckage. A blue ambulance light blinked through the haze, but the vehicle could not be seen.
There was an otherworldliness to the place where 113 men, women and children died when Air France Concorde flight 4590 dropped on to the Hotel Issimo roadside motel at 4.44 p.m. yesterday (local time).
There was a hellish, after-the-battle silence despite the black helicopters which landed and took off and the hundreds of policemen and firemen who swarmed around this place of disaster.
It was the smell you noticed first. A pungent, bitter smell of chemicals and scalded metal which burned the nostrils. A man who lay on the road before me, wrapped in a silver foil blanket while rescue workers held an oxygen mask to his face, had succumbed to this poisonous cocktail.
Take-off is the most dangerous part of a flight, when an aircraft is carrying maximum fuel - the Concorde carries 100 tonnes - and must accelerate rapidly. Aviation experts believe the pilot had already attained V1 speed, close to the Concorde's take-off speed of 350 k.p.h., when he realised that at least one of his engines was on fire.
Beyond that speed it is impossible to abort take-off. An alarm would have sounded in the cockpit as soon as the fire started. The pilot would have turned off the engine and activated fire extinguishers. To no avail.
Mr Willy Corenthin (29), an electrician for Servair, had just finished work and was driving to visit his family in Sarcelles when he saw the Concorde speeding down the runway with flames coming from its left wing.
"I parked my truck and got out to watch - all the other drivers did the same thing. The left wing exploded. The plane bolted like a horse in the sky. It was at an oblique angle to the earth, not more than 200 metres above the ground. It looked as if the pilot tried to turn back.
"It stopped over the hotel and fell. Between the explosion and the crash, it was at most 30 seconds."
The motorists who had witnessed the crash stood there for a few seconds, watching as flames shot up from the motel. "No one cried but we were all stunned. I saw a woman run out of the hotel with her hair and arm on fire. Then she tried to turn round and run back in but people held her."
There were few signs of the Concorde which was carrying 100 passengers and nine crew to New York, just a charred armrest and a wheel on the periphery of the crash area. Everything was scorched shrunken; nothing stood more than a metre or two high at the epicentre.
The remains of the Issimo motel stuck up like ribs. A gendarme with his feet apart stood with his arms crossed over his chest as if guarding the catastrophe.
It was surprising how compact an area it is, just a few hundred square metres between an untouched pine forest to the south of the road and Le Relais Bleu hotel, which had shared a parking lot with the Issimo where at least four people died.
The arbitrary nature of the tragedy was awesome: the Issimo destroyed, the three-storey, white stucco Relais Bleu, just 15 metres away, untouched save for the black smoke stains on one side.
"You see that red and white pole there?" Mr Corenthin asked, pointing beyond a cornfield. "That's a beacon, the one the Concorde was following. The explosion was very, very loud, very powerful. There was like a shock wave. But nothing exploded at the moment of the crash. It made a heavy thud when it hit the hotel. Then the flames shot up."
The residents of Gonesse, a soulless town of warehouses and little suburban bungalows, crowded behind the orange fluorescent ribbon of the police line for a peek into hell.
Most were immigrants, Africans, Arabs and Sri Lankans, and as they contemplated the swirling, grey fog before them they also, like the security forces who held them back, had blank expressions which could be interpreted as shock, anger or resignation.
Gonesse is now doomed to be remembered as the first place where a Concorde crashed. As I walked down a hill beyond the disaster site, a red and white sign informed me that this was Gonesse, "Ville Calme. Respect the speed limit," the sign admonished.
At the roundabout where I picked up a taxi back into Paris, another said: "Cemetery, funerarium".
