This remains a developing story... Please check back for possible updates...
Update (9:45 pm):
President Joe Biden spoke on Saturday evening about the shooting at former President Donald Trump's campaign rally, saying the attack, like all political violence, was "sick" and "one of the reasons we have to unite this country."
"We cannot condone this," said Biden. "The bottom line is, the Trump rally was a rally that should have been able to be conducted peacefully without any problem... Everybody must condemn it."
When asked if he believed the shooting was an assassination attempt, Biden said, "I have an opinion, but I don't have any facts."
Associated Press reporter Seung Min Kim said on social media on Saturday night that law enforcement agents had recovered "an AR-style rifle" at the scene. Later police identified the gunman killed at the scene as 20-year-old Thomas Matthew Cooks, of Bethel Park, Pennsylvania, a town about 35 miles from where the events in Butler took place.
Earlier:
Donald Trump, the presumptive Republican presidential nominee, was reportedly in "fine" condition after being wounded in an apparent assassination attempt during a campaign rally in Butler County, Pennsylvania on Saturday.
The former president appeared to be bleeding from near his ear as he was hurried off stage after a series of pops that sounded like gunshots were heard at the event. The Secret Service then brought him to his motorcade.
A spokesperson for Trump, Steven Cheung, said in a statement that the former president was being examined at a local medical facility.
Richard Goldinger, district attorney for Butler County, Pennsylvania, told the Associated Press that the suspected gunman was dead and that at least one rallygoer had been killed.
The apparent shooting happened just minutes into the campaign event, where Trump had been talking about border crossings and immigration just before the shots rang out.
President Joe Biden was briefed on the incident at about 7:15 pm.
Police cordoned off a section of the bleachers at the rally after the apparent shooting, and the New York Times reported that the Secret Service began "kicking out the press and declaring it a crime scene."
Shortly after the incident, lawmakers from both sides of the aisle issued statements condemning the apparent act of violence against a presidential candidate.
"Violence has NO place in our democracy," said California Gov. Gavin Newsom, a surrogate of the Biden campaign. "My thoughts are with President Trump and everyone impacted at the rally today."
Sen. Bernie Sanders (I-Vt.) called the attack "absolutely unacceptable."
"I am absolutely appalled by the gunshots fired at Donald Trump," said Rep. Ro Khanna (D-Calif.). "Violence is never acceptable in our democracy. I pray he was not seriously hurt and for our deeply divided nation."
Federal agencies including the Department of Justice, the FBI and the Bureau of Alcohol, Tobacco, Firearms, and Explosives were mobilizing Saturday evening to assist the Secret Service in responding to the incident.