At least 13 people were killed and another six were injured in a fire early Saturday during a birthday party at a bar in the northern French city of Rouen.

Authorities describe the fire as an accident, saying it was sparked by the candles of a birthday cake that set fire to flammable sound insulation in the ceiling of the basement room, where the celebrations were taking place.

The victims were poisoned by a toxic mix of gases released by the burning plastic, a senior police official said.

"There wasn't an explosion, it was candles used for a birthday party."

The fire started at around midnight at the Cuba Libre bar in the city centre, and firemen got to the scene at 00:20 am (2220 GMT Friday).

Interior Minister Bernard Cazeneuve said, "A fire broke out in a bar in the city centre of Rouen this evening, according to an initial investigation, 13 are dead and six are injured, and more than 50 firemen attended the scene."

Local official Laurent Labadie who was was at the scene of the blaze said the fire was the result of an accident.