"everything will be done to identify the authors" ?
Is this a translation fail ... did someone see autuer, and not grasp the subtleties of nuanced meaning.
"Culprits" would have been more appropriate. "Perpetrators" even better.
"Authors" bestows a degree of respectability on the criminals.
e2a: I did briefly look to see if I could find an original report, to see what Mr. Hollande actually said. But then I really couldn't be bothered.