The bridge collapse near the southern French city of Toulouse was possibly triggered by a truck. The truck weighed more than 45 tons, said the mayor of Mirepoix-sur-Tarn, Eric Oget, according to French media.
Investigators estimated the weight based on the size of the vehicle. It would be more than twice as heavy as the permitted maximum weight of 19 tonnes.
The disaster had come on Monday. At least one car and the truck were reportedly on the building when it collapsed. A 15-year-old and the driver of the truck died.
The authorities had previously announced that the heavy truck was used to transport construction machinery. He belonged to a construction company from the region north of Toulouse, whose offices were searched after the disaster.
The bridge had been duly monitored and had no problems at its last detailed inspection, said Dominique Alzeari, prosecutor of Toulouse. The one hundred and fifty meters long and more than five meters wide suspension bridge connected the villages of Mirepoix-sur-Tarn and Bessières. It was built in the 1930s and renovated in 2003.