Secret Service director: local police responsible for roof from which shots were fired

The US Secret Service was under mounting pressure last night over its failure to prevent the attempted assassination of Donald Trump, as its director said the agency had deemed the rooftop from which the gunman fired his rifle as outside its security perimeter and that local police were stationed inside the building in question.

- Martin Pengelly

The shooting at Trump's Pennsylvania rally was "unacceptable", Kimberly Cheatle, the service's director, said as investigations continued, adding that though "the buck stops with me", she would not resign.

"It was unacceptable and it's something that shouldn't happen again," Cheatle told ABC News, amid growing pressure to explain how the gunman had not been stopped by agents and local police.

The incident saw Trump shot in the ear, while one rally-goer was killed and two others injured. It has plunged American politics into turmoil, ramping up fears of political violence in a presidential election campaign that is already marred by concerns over civil unrest.

But it has also prompted handwringing over how such a security lapse could happen given the intense security presence around Trump, led by the Secret Service.

Trump was speaking on Saturday at the Butler county showgrounds in rural western Pennsylvania when the gunman climbed on to a rooftop near the rally and opened fire, before being killed by return fire from law enforcement officers.