Tunisian security sources told Reuters that Bouhlel hailed from the town of Msaken and last visited four years ago.
Two French police officials told the Associated Press that identification found alongside the driver belonged to a 31-year-old Frenchman of Tunisian descent. He had a petty crime record, but no known link to extremist groups.
The man was a Nice resident, the AP reported. It was not immediately clear how long he lived in France.
The officials spoke to the wire service on the condition of anonymity because they were not authorized to comment publicly on the attack.
The suspect was described by Nice media as a father, delivery driver and loner who was not known to be particularly religious. Authorities were not sure if he was the only one involved in Thursday's attack.
No group has claimed responsibility for the attack.