The offers of help from the public mirrored what happened in Manchester last week, reported the Daily Telegraph.
British armed police rushed to three incidents incentral London on Saturday after a van ploughed into pedestrians on London Bridge and reports of multiple stabbings in the nearby Borough Market area.
Police sent out security advice to Londoners on Twitter saying "run, hide, tell" if they were caught in an attack. The BBC cited police as saying there had been more than one fatality.