The US Department of Homeland Security is launching an open investigation into security lapses that resulted in the Republican presidential candidate Donald Trump’s attempted assassination during a weekend rally last week, announced the federal department on Wednesday.

The probe will “evaluate the United States Secret Service's process for securing former President Trump's July 13, 2024 campaign event," the office of the DHS inspector general said in a statement.

President Joe Biden said on Monday that he has conducted an independent investigation into the security at the rally "to assess exactly what happened,” adding that the investigation results will be revealed to the public. However, it remains unclear whether this probe aligns with the review announced by the Department of Homeland Security's inspector general.

Security preparations were questioned following Trump’s attempted assassination by a 20-year-old Pennsylvanian man, Thomas Matthew Crooks. A Secret Service agent shot the assailant after he opened fire at the former president’s rally without a clear motive.

Crooks' assassination attempt caused the death of an individual, critically injured two spectators, and wounded Trump's right ear as he was delivering a speech to his supporters before the upcoming elections.

The Secret Service is a division of the DHS, and it is responsible for ensuring the safety of former and current US presidents, and presidential candidates.

DHS, FBI concerned about 'retaliatory violence' after Trump attack

Based on a joint intelligence bulletin, Politico stated that the FBI and the US Department of Homeland Security (DHS) are worried about "retaliatory acts of violence" following the failed assassination attempt on Republican presidential nominee Donald Trump last week.

Published on Monday, the bulletin stated, "The FBI and DHS remain concerned about the potential for follow-on or retaliatory acts of violence following this attack, particularly given that individuals in some online communities have threatened, encouraged, or referenced acts of violence in response to the attempted assassination."

While potential targets are not named in the text, it is said that "election-related targets" are more vulnerable to attacks and other "types of disruptive incidents." Security agencies also point out that terrorists have previously plotted attacks against "perceived political or ideological opponents."

Moments after the shooting, security was able to approach Trump's podium to evacuate him. Trump appeared to have sustained mild wounds, as blood was seen running from the side of his head. 

"In this moment, it is more important than ever that we stand United, and show our True Character as Americans, remaining Strong and Determined, and not allowing Evil to Win," he wrote on his social media network Truth Social.

Secret Service Director Kimberly Cheatle, in her first major statement since the shooting, revealed that the agency is ramping up security measures for Trump.

"I am confident in the security plan our Secret Service RNC coordinator and our partners have put in place, which we have reviewed and strengthened in the wake of Saturday's shooting," Cheatle stated.

She also mentioned that adjustments have been made to Trump's security detail to ensure his safety throughout the convention and the rest of the campaign.