The US Secret Service is investigating how a gunman armed with a rifle was able to get close enough to shoot and injure Donald Trump.
The assassination attempt left the former president with a bloody ear.
One man was killed and two others were injured.
Joe Biden says there'll be an independent review into national security at the Pennsylvania rally.
Matt Shoemaker is a Former intelligence officer at the Defence Intelligence Agency:
"From my perspective, this looks like this may have been a failure on the law enforcement, the second tier level. And the reason why is because the communication between local law enforcement and Secret Service is oftentimes delayed, and in these sorts of situations, times of the essence".
