French anti-terrorism police have arrested seven people in Strasbourg and Marseille who had been plotting an attack on France for several months, the interior minister said Monday.

Interior Minister Bernard Cazeneuve said a series of arrests in June and this past Sunday put an end to the plot and “allowed us to thwart a terrorist act that had been envisaged for a long time on our soil,” Cazeneuve told reporters in Paris.

The suspects are believed to have initially wanted to target the Euro 2016 European soccer tournament earlier this year but their plans later evolved, according to a security official. The official was not authorized to be publicly named speaking about ongoing investigations.

Cazeneuve didn’t identify the target of the planned attack, but said investigators are studying whether it was part of a larger plot to attack multiple sites simultaneously.

The suspects are French, Moroccan and Afghan, and are between 29 and 37 years old. Cazeneuve said six of them hadn’t been known to intelligence services, and one was a Moroccan who had been flagged to France by a foreign government.

One of the suspects worked for the Strasbourg city government on special events, Strasbourg metropolitan area president Robert Hermann said, according to his office.

The arrests rattled nerves in Strasbourg because they came just five days before the opening of the Alsacian city’s famed Christmas market, which attracts tourists from across Europe and was the target of a failed extremist plot in 2000.

However, Mayor Roland Ries said the case had no direct link to the market, so the event will open as usual Friday — under heavy security.

The raids in Strasbourg took place in the Neuhof and Meinau neighborhoods, where authorities dismantled a jihadi network in 2014 that included the brother of an Islamic State bomber who attacked the Bataclan concert hall in Paris last year.

French police have detained 418 people this year in terrorism investigations following deadly Islamic State attacks, Cazeneuve said.

(AP)