Former US president and current presidential candidate, Donald Trump, has been injured in shooting incident in his Pennsylvania rally.

Several shots were heard during the incident that left two people dead and two others critically injured.

Live video showed blood on the right side of Trump's face and ear.

He was then seen holding his hand to his ear and falling to the ground behind the podium, after which his security team escorted him off stage.

His campaign alleged in a statement that the Republican nominee was "fine" and being checked at a medical facility.

Giving his first account of the incident later, Trump said in a post on his Truth Social site, "I was shot with a bullet that pierced the upper part of my right ear.

I knew immediately that something was wrong in that I heard a whizzing sound, shots, and immediately felt the bullet ripping through the skin."

"Much bleeding took place, so I realized then what was happening."

Butler County District Attorney Richard Goldinger, meanwhile, said two people had died during the incident, including an apparent shooter.

Speaking to Reuters, a source said the shooter was dead and the Secret Service was investigating the shooting as an "assassination attempt."

The shooter's identity and motive was not immediately clear.

In his post, Trump identified one of the fatalities as a “person at the rally,” saying “another person was badly injured.”

The Secret Service later said two had been “critically injured.”

Reacting to the incident, President Joe Biden said in a statement on X that he was "grateful to hear that he (Trump)'s safe and doing well.”

“I’m praying for him and his family and for all those who were at the rally, as we await further information."

Former president Barack Obama also posted on X, saying, "We should all be relieved that former president Trump wasn't seriously hurt.”