People fled bars and restaurants in Nice in panic Monday after a man fired a noisy but harmless alarm gun into the air in the southern French resort town, police said.
Around a dozen people were lightly injured, some requiring hospital treatment, as people rushed out of bars and cafes fearing an attack, emergency services personnel told AFP.
France has been hit by a string of terror attacks in recent years, raising the levels of security, and concern, in the country.
Last month, an Islamist gunman who killed four people and injured four others in a shooting spree in southwestern France.
Nice suffered a terrible attack in 2016 when a Tunisian man ploughed a truck through a large crowd gathered for Bastille Day fireworks in the Mediterranean city, killing 86 people and injuring more than 400.
Monday's incident was the result of dispute between two couples.
In a tweet, local mayor Christian Estrosi thanked local traders who sounded the alarm, allowing police to arrest the person wielding the alarm gun.