Updated

Prosecutors say seven men and a woman have been arrested in France on suspicion of planning to join radical Islamic groups fighting in Syria.

The prosecutor's office says French intelligence agents are questioning the eight Tuesday, one day after their arrests in and around Paris. In France, terror suspects can be held for up to four days before being charged or freed.

More than 20 French citizens have been killed in Syria's 3-year-old civil war. In November, France opened an investigation into more than 600 French people who either are preparing to join the fighting or are already there.

The probe secured its first convictions Friday, when three men were found guilty of planning to join jihadist groups in Syria and received prison sentences of two to five years.