I found out what happened re: gunfire here in Gracia. Just before dawn on Friday, a car tried to escape a police roadblock on the Travesera de Dalt, headed down Torrent de les Flors, and the cops fired on the car near the corner of Torrent and Legalitat. The car stopped and those inside were arrested; the driver was an Iraqi. Nothing to do with terrorism, we have been assured.
I don't think it was a very good idea for the police to shoot at a car in the middle of Europe's most crowded residential neighborhood, unless the car contained extremely bad people who could not possibly be allowed to get away. If these guys were just car thieves or hash smugglers, they should have kept the guns holstered.