I know grendelsmere is going to nitpick my translation, but some screwing up my eyes and a little bit of Babelfish (for the rest of the release) tells me that
"Les policiers ont été repérés par les manifestants au moment où ils ont refusé de lancer des projectiles."
"The officers were located by the demonstrators when they refused to launch projectiles."
Now, I watched the video. I heard the demonstrators telling the officers to put the rock down. So the Quebec police aren't just muddying the waters, they are outright lying. They're inverting the truth without regard to the perfectly good evidence.
Just goes to prove that all coppers are bastards.
EDIT: As grendelsmere points out, that sentence of the press release reads better if you translate it as "The police officers cover was blown when they refused to throw things."