London Has Fallen (2016) on Netflix

The President goes to London along with several World leaders to attend the funeral of the Prime Minister who died suddenly. But after arriving all of the leaders are attacked and killed. The President because of his security man, Mike Banning gets away. But the ones behind the attack still pursue them. They try to get away in the President's helicopter but they manage to shoot it down. The President and Banning are now on foot and are trying to find a safe haven. In Washington, the Vice President gets a call from a man who claims responsibility; he's a man they tried to eliminate with a drone but killed his family instead. Evidently he wants revenge.