That was the CRS (Compagnies Républicaines de Sécurité). They've been packing them since at least the early '80s and my guess is that they still have the same guns. I tried asking them about their Mini 14s once but they aren't the least bit chatty.
That really looks like a Benelli M4/M1014 shot gun, not a Mini-14.
A pal of mine, retired SFPD Inspector and former tank platoon commander, was in Paris during the first attack, a few hundred meters from his hotel. He got his fellow tourists away from the doors, and played doorman along with an unarmed hotel security guard until the CRS showed up, who figured they had too many doors and too much glass to deal with for the two of them, their partners being detailed to the Eiffel Tower and Pullman Hotel, and so my pal and the hotel guard were *deputized*, and outfitted from the trunk of the cops' car. With, among other playthings, a Mini-14 and a folding stock Remington 870 shotgun. And then it was not two understaffed cops, but a reasonably effective fire team that could cover each other and perform fire-and-movement if needed.
An interesting point from that evening: most of the cops were using the straight 20-round magazines rather than the longer curved 30-round versions, which resemble the magazine of an AK-47 a little too much. It doesn't pay to confuse your own snipers.