Police in Paris arrested a man in an underground car park in connection with a series of shooting in the city earlier in the week.
The man was held in a car park in the suburb of Bois-Colombes.
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The Ukip leader confirmed he had "no prior warning" of Douglas Carswell's resignation from the party as he hit out at the "staunch Tory".
Two knives were found at the scene in Islington, North London, and the suspects fled on foot before being arrested.
The violence began after a counter-protester allegedly doused a female rally organiser with pepper spray.