Multiple shots rang out at Donald Trump's rally in Pennsylvania on Saturday, with the Republican presidential candidate grimacing and raising his right hand to his right ear as shots rang out, video footage showed.

The former president had just started his speech when gunshots erupted and Trump and other rally attendees hit the deck. Secret Service agents swarmed around him and live video showed blood on the right side of Trump's face and ear.

Trump repeatedly raised his fist in the air, with an American flag visible behind him, as security ushered him away.

"The Secret Service has implemented protective measures and the former president is safe," a spokesman for the agency said on X after what it called an incident. "This is now an active Secret Service investigation and further information will be released when available."

The suspected shooter was dead, as was an audience member, and another person was in critical condition, a Washington Post reporter said on social media, citing the Butler County district attorney.

One witness, Ron Moose, said he heard what sounded like four shots, describing the sound as "pop, pop, pop."

Trump's campaign spokesman said Trump was fine and that he was being checked out at a local medical facility.

"President Trump thanks law enforcement and first responders for their quick action during this heinous act. He is fine and is being checked out at a local medical facility. More details will follow," Trump campaign spokesman Steven Cheung said in a statement.

The venue was abandoned with chairs knocked over and yellow police tape around the stage. A helicopter flew above and law enforcement officers walked through the area, the video feed showed. Armed law enforcement officers were also seen on a roof near the stage where Trump was standing.

U.S. President Joe Biden received an initial briefing on the incident, the White House said.

This is a developing story and will be updated with additional information.