WASHINGTON — President Joe Biden Sunday called for unity and pledged an independent review following the campaign rally in Butler, Pennsylvania, on Saturday where former President Donald J. Trump was shot and injured.

“An assassination attempt is contrary to everything we stand for as a nation,” Biden said in remarks from the White House, adding that “there is no place in America for this kind of violence or any violence for that matter.”

Biden said the independent review will “assess exactly what happened and we’ll share the results of that independent review with the American people as well.”

Biden also will address the nation from the Oval office Sunday night at 7 p.m. Central time about the assassination attempt on Trump.

“Unity is the most elusive goal of all, but nothing is (more) important than that right now,” Biden said. “We’ll debate and we’ll disagree, that’s not going to change. But we’re not gonna lose sight of the fact (of) who we are as Americans.”

Biden added that he is directing the U.S. Secret Service to assess the security measures for the Republican National Convention beginning Monday in Milwaukee, Wisconsin, where the GOP will formally nominate Trump for president.

Trump wrote on Truth Social that he was initially planning to delay his trip to the RNC by two days, but said he could not “allow a ‘shooter,’ or potential assassin, to force change to scheduling, or anything else” and so would arrive later Sunday.

Outraged congressional Republicans on Sunday demanded answers from the Secret Service as to how the shooter was able to access a rooftop within range of the former president, and committee leaders from both parties began planning hearings and probes. The FBI is investigating the shooting as an attempted assassination.

South Carolina Republican Sen. Lindsey Graham said on NBC’s “Meet the Press” he was grateful the former president “survived an assassination attempt,” and noted how dangerous the situation was.

“How could this happen?” Graham asked. “How could somebody get within 130 yards of the president with a rifle?”

Pennsylvanian killed

Several loud pops rang out as Trump was beginning a campaign event Saturday that quickly ended with him cupping blood on the side of his face and defiantly pumping his fist at the crowd and shouting “Fight, fight, fight,” before he was whisked off-stage by Secret Service agents.

Trump was injured but pronounced safe by the Secret Service and he later wrote on his social media site Truth Social that he was shot “with a bullet that pierced the upper part of my right ear.”

An attendee at the rally was killed, and two others were injured in the shooting.

Pennsylvania Democratic Gov. Josh Shapiro on Sunday identified the person killed as Corey Comperatore. Local news reports said he was a former fire chief.

“Corey died a hero,” Shapiro said during a news conference. “Corey dove on his family to protect them last night.”

Shortly after the shooting, Secret Service spokesperson Anthony Guglielmi said in a statement the shooter “fired multiple shots toward the stage from an elevated position outside of the rally venue,” and Secret Service personnel shot and killed the individual.

The FBI identified the shooter as Thomas Matthew Crooks, 20, of Bethel Park, Pennsylvania.

Congressional Republicans said they want answers from the Secret Service about how the event unfolded and if there were any security shortcomings.

The Secret Service is responsible for the safety of current and former presidents, and certain government officials.

Guglielmi on Sunday morning on X addressed “an untrue assertion that a member of the former President’s team requested additional security resources & that those were rebuffed.”

He said that was “absolutely false.”

“In fact, we added protective resources & technology & capabilities as part of the increased campaign travel tempo,” he said.

The agency falls under the Department of Homeland Security, and congressional Republicans have clashed with DHS Secretary Alejandro Mayorkas, to the point of impeachment. The Senate, controlled by Democrats, dismissed the two articles of impeachment.

House GOP inquiry

Hours after the Saturday night shooting, House Speaker Mike Johnson wrote on X that the House will conduct an investigation of the incident.

On the “Today” show Sunday, Johnson said that the House’s probe will “determine where there were lapses in security and anything else that the American people need to know and deserve to know.”

Republican Rep. Mark Green of Tennessee, who chairs the House Homeland Security Committee, wrote a letter to Mayorkas saying he was concerned how the shooter was able to “access a rooftop within range and direct line of sight of where President Trump was speaking.”

“The seriousness of this security failure and chilling moment in our nation’s history cannot be understated,” Green wrote in the letter. “Had the bullet’s trajectory been slightly different, the assassination attempt on President Trump might have succeeded.”

Green asked Mayorkas to provide the committee with several documents by July 22, such as the security plan for the rally, Secret Service protocol for assassination attempts and copies of briefing materials given to Biden and Vice President Kamala Harris about the incident.

Republican Sen. Josh Hawley of Missouri sent a letter to Homeland Security and Governmental Affairs Committee Chair Gary Peters of Michigan to push for an investigation into the shooting.

Montana Democratic Sen. Jon Tester, who also sits on the committee, made the same request, and argued the need for an investigation because “individuals and groups will use yesterday’s tragedy to sow division in our country,” and that the committee “can help push back on those efforts by investigating and publicizing the facts surrounding yesterday.”