'Enough is enough' May says after London attackers kill seven

By Andy Bruce and Alistair SmoutLONDON (Reuters) - Prime Minister Theresa May said Britain had to be tougher instamping out Islamist extremism after attackers killed at least seven people by ramming a van into pedestrians on London Bridge and stabbing revellers in nearby bars.After the third militant attack in Britain in less than three months, May said Thursday's national election would go ahead."It is time to say enough is enough," the Conservative leader said outside her Downing Street office