Three men have been handed preliminary terror-linked charges after a failed attack at a residential building in Paris.
The incident occurred at an upscale Paris neighbourhood with gas canisters that failed to ignite.
A judicial official said on Saturday the three men were placed under formal investigation on Friday after the mysterious attack attempt.
The official was not authorised to speak on the record in an ongoing investigation.
Anti-terrorism prosecutor Francois Molins said at a news conference on Friday that investigators have yet to find a "logical explanation" for why the building was targeted.
Two of three men, identified as Aymen B. and Amine A., are among thousands on a list for radicalisation.
Aymen B.'s cousin, Samy B., also was charged.
All were held for attempted murder linked to a terrorist enterprise and transporting explosives.