He tweeted: “A gun attack took place. Thank you to the police for their quick action. The Mayor @ACORDEBARD goes there. We discuss with @prefpolice and the Public Prosecutor’s Office to understand what happened.
“Thoughts for the victims and witnesses of this tragedy.”
An emergency services official in the city said multiple people were wounded, but did not provide further details.
The prosecutor’s office has opened a murder investigation.
Anti-terrorism prosecutors are investigating the shooting, but have not declared whether there was a terrorist motive.
A string of deadly attacks by Islamic extremists rocked France in 2015-16. The country remains on alert for terrorism-related violence.