PARIS (AP) — Ten people suspected of using encrypted social networks to prepare a possible attack were arrested Tuesday during counterterrorism operations in France and Switzerland aimed at clarifying details of the alleged plot, according to French officials.

A 23-year-old Colombian woman and 27-year-old Swiss man, both targets in a Swiss investigation of the Islamic State group, were among the suspects detained.

Counterterrorism investigators detained nine people between the ages of 18 and 65 in France and one person in Switzerland, according to a French judicial official. The official, who spoke on condition of anonymity to discuss an ongoing investigation, would not provide details about their identities.

The suspects were being questioned following searches of properties in the Paris suburbs and in southeastern France. Some of the suspects previously had been flagged for alleged Islamic radicalization, according to the judicial official and a French police official. Two are brothers, the officials said.

The Swiss suspect, who was among those arrested in France, allegedly had ties to a 13-year-old who was arrested earlier on suspicion of plotting a knife attack, the judicial official said.

The mayor of the French Riviera city of Nice, Christian Estrosi, thanked police for the arrests. His office said Estrosi was speaking with France's interior minister about the investigation, but neither City Hall nor the judicial official would confirm reports that the suspected attack plot targeted Nice.

The city remains scarred after the July 2016 truck attack that killed 86 people watching a Bastille Day fireworks display from a seaside promenade.

A French security official said the alleged plot did not appear to be fully developed but authorities acted Tuesday out of concern that the group was moving toward action.

In parallel to the Swiss investigation, French authorities opened a probe in July focused on suspicious activity by a person in Switzerland using the encrypted Telegram network, according to the French judicial official. The suspect, based in Switzerland, had communicated with people in France on social networks about unspecified violent acts, the official said.

Among the French towns targeted in the operation were Aix-en-Provence in southern France and Menton on the Mediterranean coast, as well as Paris suburbs, according to a French security official.

The office of Swiss Attorney General Michael Lauber said the arrest there followed searches of buildings in the French-speaking Vaud and Neuchatel regions of western Switzerland.

The Swiss investigation originally targeted a 27-year-old Swiss man and was more recently extended to include the Colombian woman, neither of whom was identified by name. Lauber's office said the woman was expected to remain in custody until she appears before a court.

The arrests came days after a new counterterrorism law took effect in France. The law replaces a state of emergency that had been in place since the deadly Paris attacks.

French Interior Minister Gerard Collomb appeared to downplay the arrests, telling reporters during a visit to Germany on Tuesday that, "in a relatively habitual way, we arrest a certain number of individuals who appear that they could be dangerous."

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Jamey Keaten reported from Geneva. Geir Moulson in Berlin contributed to this report.