The Oversight Committee – the main investigative board of the US House of Representatives – has summoned US Secret Service Director Kimberly Cheatle to testify at a hearing on 22 July.

"Americans demand answers about the assassination attempt of President Trump," the panel said in a statement on social media.

At a news conference earlier, FBI special agent Kevin Rojek said “it is surprising” that the gunman was able to open fire on the stage before the Secret Service killed him.

But when asked if there was a failure of security, he said they were "not gonna make that assessment" with an active investigation.

The Secret Service was not at the news conference.

How did the night unfold?

Donald Trump was speaking at a campaign event in the city of Butler, Pennsylvania on Saturday night when a gunman attempted to assassinate the former president.

Here's a breakdown of how that all unfolded. All times are local:

• 17:00:Trump was scheduled to start addressing the crowd
• 18:03:He takes the stage to Lee Hazelwood’s “God Bless the USA”
• 18:11:Just a few minutes into his campaign speech, loud shots ring out
• 18:12:Secret Service agents swarm the former president before he is rushed off stage with blood near his ear and on the side of his face
• 18:14:Trump's motorcade leaves the rally
• 18:42:Secret Service issuesa statement
• ,external
• , confirming that Trump is safe and there is an active investigation into the incident
• 19:03: Trump’s campaign says he's “fine”
• 19:45:Law enforcement confirms that the suspect is dead, along with an audience member
• 20:13:Biden condemns the attack and says during a briefing that he is trying to speak with Trump over the phone as soon as possible
• 20:42:Trump shares his first account of what happened, saying a bullet pierced his upper part of his right ear
• 21:33:The FBI Pittsburgh says it is the lead federal law enforcement agency in the investigation

(Pieced together from BBC reports)