A policewoman's 20th birthday party ended in tragedy early yesterday (Saturday) when the candles on her cake sparked an inferno at a bar in Rouen, killing 13 people and injuring six others.
An urgent investigation is under way amid questions about whether the Cuba Libre bar in the northern French city complied with fire regulations.
The policewoman, named as Ophelie A., was among those who died in the bar's cramped basement. The victims were all aged between 18 and 25.
One guest, who suffered burns to 90 per cent of her body, is fighting for her life at a hospital in Paris.
The blaze broke out at midnight after a guest or staff member stumbled while carrying the birthday cake, lit with candles and sparklers, down steep wooden stairs into the basement.
Witnesses said the walls were covered with a soundproof material that caught fire immediately. The basement, packed with about 20 people, rapidly filled with smoke and toxic fumes.
One customer, Stephanie, 31, said: "I was on the ground floor of the bar. We saw the flames, it was like a flame-thrower." Another witness Amar Ould Said, 40, said: "They were bringing bodies out every two minutes. They set up a first aid area on the pavement across the road." Some of the dead were so badly burned that they remained unidentified last night. Frantic relatives rushed to Rouen hospital where psychologists counselled the bereaved. At least 50 people were searching for missing friends or family.
The horrific fire plunged Rouen into profound shock for the second time in 10 days after Islamist terrorists slit the throat of an 85-year-old priest in nearby Saint-Etienne-du-Rouvray. Initial reports of the fire raised fears of another attack, but the mayor Yvon Robert said it was "completely accidental".
The basement where partygoers were trapped reportedly had "no proper fire exit", said regular customers.
The bar is popular with people from Reunion, an Indian Ocean island which is part of France. Rouen is home to a sizeable Reunionnais community.
One customer told Le Parisien newspaper: "It's a real mousetrap. Could you see an illuminated sign, an exit route or a way out? Nothing like that. In the panic, how would you get out?"
There was a door leading from the basement to a corridor and garages behind the bar, but the guests appear not to have managed to exit through it, although firemen used it to gain access.
President Francois Hollande expressed his "sadness", promising: "Everything will be done in the judicial investigation in progress to determine the causes of this dramatic accident."