Washington: A shooting at former US President Donald Trump's rally in Pennsylvania on Saturday (local time) has sparked concerns about political violence and increased awareness of past attacks and assassination attempts against presidents and candidates, CBS News reported.

There have been multiple instances of past attacks on US presidents, former presidents, and major-party presidential candidates. Direct attacks targeting US Presidents, Presidents-elect, and candidates have occurred on 15 occasions, with five causing death, CBS News reported, citing a 2008 report compiled by the Congressional Research Service.

Of the 46 individuals serving as US President, 13 have been subject to actual or attempted assassinations, the number does not mention the Pennsylvania shooting incident involving Trump. At least seven of the past nine presidents have faced assaults, attacks, or assassination attempts.

According to the Congressional Research Service report, presidents who survived attacks include Gerald R Ford (twice in 1975), Ronald W Reagan (a near-fatal shooting in 1981), Bill Clinton (when the White House was fired upon in 1994), and George W Bush (when an attacker threw a grenade that did not explode towards him and the president of Georgia during an event in Tbilisi in 2005), according to CBS News report.

There have been attack attempts on US President Joe Biden and former US Presidents Barack Obama, Donald Trump and Joe Biden, the latest Congressional Research Service report said, citing the Secret Service as the source.

Two others who served as US presidents were attacked. US President-elect Franklin D Roosevelt was attacked in 1933, while US presidential candidate, Theodore Roosevelt, was targeted in 1912 when he was seeking the presidency after being out of office for nearly four years.

Two other presidential candidates - Robert F Kennedy, who was killed in 1968, and George C Wallace, who was seriously injured in 1972 were also victims of direct assaults, the report compiled by the Congressional Research Service said.

Four US presidents have been assassinated, including Abraham Lincoln, James A Garfield, William McKinley, and John F Kennedy. Among the 15 attacks mentioned in the report, only Lincoln was assassinated due to a broad conspiracy, according to the report. However, conspiracy theories still surround many of these events.

The Lincoln assassination was proven to be a broad conspiracy in only one incident. Although such contentions have arisen on multiple occasions.

Only one other incident involving more than one participant was the 1950 assault on Blair House, the temporary residence of then-US President Harry S Truman. However, no evidence regarding conspirators emerged from the subsequent investigation or prosecution.

Among the 18 attacks or assassination attempts on US presidents or presidential candidates, all but two involved firearms. All but two of the attacks, both against Gerald R Ford, were carried out by men. All but one of the 15 assaults took place in the US, according to CBS News report.

The first attack took place in 1835, when an attacker's pistol misfired against then-US President Andrew Jackson, according to the Congressional Research Service and the attacker, Richard Lawrence, was declared insane. According to the report, the attacker said, "Jackson was preventing him from obtaining large sums of money and was ruining the country."

The latest shooting incident involved Donald Trump's rally in Pennsylvania. Trump was on stage at a campaign rally in Pennsylvania's Butler before gunshots rang out and Secret Service agents stormed the stage. The Secret Service agents surrounded the Republican candidate and escorted him off the stage, with blood visible across his face.

He raised his fist towards the crowd as he was escorted away by law enforcement personnel. One of the rally attendees was killed, while two more were critically injured, CNN reported. The gunman was also killed by US Secret Service agents. Donald Trump said that the bullet pierced the upper part of his ear.

The Federal Bureau of Investigation (FBI) has identified the gunman involved in the assassination attempt against Donald Trump as Thomas Matthew Crooks. It further said that an investigation is underway into the shooting incident, CNN reported.

In a statement, the FBI said, "The FBI has identified Thomas Matthew Crooks, 20 of Bethel Park, Pennsylvania, as the subject involved in the assassination attempt of former President Donald Trump on July 13 in Butler, Pennsylvania."

"This remains an active and ongoing investigation, and anyone with information that may assist with the investigation is encouraged to submit photos or videos online at FBI.gov/butler or call 1-800-CALL-FBI," it added.

The FBI has termed the shooting at Trump an attempted assassination. FBI special agent in charge of the Pittsburgh office, Kevin Rojek, said, "This evening, we had what we're calling an assassination attempt against our former President Donald Trump. It's still an active crime scene."

He said that the FBI has deployed investigative agents, evidence response teams, and other personnel from across the country, according to CNN report.

Lt Col George Bivens of the Pennsylvania State Police stated that the investigation would allow authorities to "take a look at where any failures occurred and what can be done better in the future," CNN reported.

While addressing a news conference in Butler, Pennsylvania, authorities said the victims of the shooting have been identified. However, details regarding the incident have not been publicly shared.Lt Col Bivens said that all three were adult men.

He said, "We have notified a number of family members, but they have not had an opportunity to notify extended family." He further said that gunshots had been "scattered," and weren't hitting just one location in the crowd, according to CNN report.

Donald Trump, in his first account of being shot at during a rally in Pennsylvania, has said that the bullet fired at him "pierced" the upper part of his right ear. Trump said that he immediately knew something was wrong.

He also thanked the US Secret Service and law enforcement for their rapid response to the shooting that just took place in Pennsylvania's Butler. He also offered condolences to the family of a person who was killed at the rally and the person who was injured.

In a post on Truth Social, Trump stated, "I want to thank The United States Secret Service, and all of Law Enforcement, for their rapid response on the shooting that just took place in Butler, Pennsylvania. Most importantly, I want to extend my condolences to the family of the person at the Rally who was killed, and also to the family of another person that was badly injured."

"It is incredible that such an act can take place in our Country. Nothing is known at this time about the shooter, who is now dead. 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. GOD BLESS AMERICA," he added.

(With Inputs From Agencies)