Five questions for Secret Service after Trump shooting

Several major questions have emerged for the US Secret Service to answer in the aftermath of the shooting of Donald Trump at a rally in Pennsylvania.

The FBI has taken on the role of lead investigator into the incident, during which one person was killed and two others critically injured - while Trump was wounded in the ear. As the US demands answers, the Secret Service director has been summoned to testify before a committee of the US House of Representatives on 22 July. Here are some of the things that security experts are asking about.

Why was gunman's roof not secured in advance?

It remains unclear how suspected gunman Thomas Matthew Crooks got access to a roof of a building near the rally that was little more than 130m (430 ft) from Trump.

The rooftop was a known vulnerability before the event, according to NBC News, which cited two sources familiar with Secret Service operations.“Someone should have been on the roof or securing the building so no one could get on the roof,” NBC quoted one of the sources as saying.

As well as the access question, it has been suggested that the line of sight from the rooftop to Trump's podium area should have been blocked off.