Paris prosecutor's office on Wednesday opened an investigation into the motorway bridge collapse in Italian city of Genoa, state-run France info radio reported.

An inquiry into "involuntary homicide and ... injuries" had been launched after foreign ministry confirmed four French nationals were among the dead.

One of the victims was from Tarn, southwest France and two others were from southern town of Toulouse, according to BFMTV news channel.

On Tuesday, about 100-meter section of Morandi Bridge collapsed amid torrential rains. At least 39 people were killed in what Italian authorities called "an immense tragedy."

Built in the 1960s, the bridge links port city of Genoa with France's southern regions.