(NewsNation) — Department of Homeland Security Secretary Alejandro Mayorkas, FBI Director Christopher Wray, and Secret Service Director Kimberly Cheatle have been asked to speak to lawmakers at a Congressional hearing next Tuesday about the attempted assassination of former President Donald Trump.

Rep. Mark Green, R-Tenn., the chairman of the House Committee on Homeland Security, said he’s calling for the hearing because “the American people want answers” about the circumstances surrounding the Saturday shooting at a Trump rally.

“Secretary Mayorkas and Director Cheatle are responsible for the department and the agency charged with securing our homeland and protecting our nation’s chief executives and candidates, while Director Wray leads the agency with the vital responsibility of investigating this attempted assassination,” Green said in a statement. “It is imperative that we partner to understand what went wrong, and how Congress can work with the departments and agencies to ensure this never happens again.”

The FBI said Sunday that a 20-year-old gunman attempted to assassinate the former president at a campaign rally Saturday in Butler, Pennsylvania. The gunman, identified as Thomas Matthew Crooks, was up on a building around 130 yards away from Trump’s stage, was killed seconds after Trump was shot.

A U.S. Secret Service source told NewsNation that local authorities were assigned to cover the building where Crooks shot his weapon.

According to the USSS source, it’s standard for local police to handle areas outside the perimeter of an event because they know them better.

While a local officer checked on the roof and found the shooter, the source said he did not engage because he couldn’t reach his weapon and Crooks’ gun was pointed at him.

Two attendees, David Dutch, 57, and James Copenhaver, 74 were wounded, and the former fire chief for South Buffalo Township, Corey Comperatore, 50, was killed as he shielded his family from the fire.