French security agents have arrested six people on preliminary terrorism charges for allegedly plotting to attack French President Emmanuel Macron, according to a French judicial official.

The official, speaking on condition of anonymity to discuss the allegations, said intelligence agents detained the six in three widely scattered regions, including the Alps, Brittany and near the Belgian border. He said the plan to target the French president appeared to be vague and unfinalized but violent.

Authorities released no further details about the six suspects and did not say if they were suspected of working together or separately.

French presidents have been targeted several times over the decades, including in 2002 when a far-right sympathizer tried to attack President Jacques Chirac on the Champs-Elysees Avenue in Paris during Bastille Day celebrations.

Macron was in the northeastern French city of Verdun on Tuesday as part of centenary commemorations for the end of World War I.

The suspected plot was uncovered days before U.S. President Donald Trump and dozens of other world leaders are due in France for commemorations this weekend of the signing 100 years ago of the Nov. 11 armistice that ended World War I.