Police have said Edinburgh Airport will reopen after concluding that "there is no threat" at the site, a spokesman told reporters.
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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.