The head of the United States Secret Service has acknowledged to Congress that the agency did not successfully thwart an assassination attempt on former President Donald Trump during a campaign rally on July 13 in Pennsylvania.

“We failed. As the director of the United States Secret Service, I take full responsibility for any security lapse,” Director Kimberly Cheatle stated on Monday while testifying before the Committee on Oversight and Accountability in the US House of Representatives. Cheatle is currently facing calls from Republicans for her resignation.

“The assassination attempt on former President Donald Trump on July 13 represents the most significant operational failure at the Secret Service in decades,” Cheatle noted.

“There was a clear mistake, and we will make every effort to ensure that this never happens again,” she added.

During the outdoor campaign rally, Trump was wounded in the right ear by the shooting, which also resulted in the death of one attendee and injuries to two others.

The suspected shooter, 20-year-old nursing home aide Thomas Matthew Crooks, was killed by law enforcement on the scene. The motive behind the attack remains unclear.

Cheatle revealed that Crooks had been identified as “suspicious” before Trump took the stage, but was not considered a “threat” at the time.