A railway station in Nimes, southern France, was evacuated Saturday evening after a witness reported one or more armed individuals.
Police were also reported to have boarded a train and ordered passengers to put their hands up in the air while they searched for suspects, according to reports on social media.
Another security official said police are working to verify whether the incident had any link to the attacks Thursday around Barcelona.
Reports indicated that people in the area heard shots being fired at the station and that three men allegedly exited the train afterwards.
Local authorities advised passengers to avoid the train station until further notice.
The Tour of Spain cycling race kicked off from Nimes earlier Saturday (local time) under heavy security.
While law enforcement agencies at present say the reports were unfounded, one person has been detained for "other reasons" following "suspicious activity".
French authorities stepped up controls on the border with Spain after the Barcelona attacks.