Lawmakers investigating the assassination attempt of former president Donald Trump visited the site of the shooting in Butler, Pa., Monday and said they were working methodically to produce a definitive, nonpartisan account of an event whose facts remain murky.

The nine members of a House of Representatives task force toured the Butler Farm Show grounds and met with local law enforcement officials. Several members expressed astonishment at the proximity — about 430 feet — between the rooftop where 20-year-old Thomas Matthew Crooks took aim on July 13 and the podium from which Trump was speaking to a crowd of his supporters.

“When you’re actually walking these grounds, when you’re actually going to the building, when you’re actually up on the roof … if you can actually look at that, right now, in person … it’s like, okay, I got it, I know where that was,” said Rep. Mike Kelly (R-Pa.), who represents the Butler area.

The visit was led by Kelly, the panel’s chairman, and Rep. Jason Crow (D-Colo.), an army Special Forces veteran who is the ranking Democrat.

The task force, established July 29 by a unanimous vote, is composed of seven Republican and six Democratic lawmakers. It has subpoena authority and has assumed control over all House committee investigations into the assassination attempt and the security lapses that surrounded it.

Crooks was able to fire eight times before he was killed by Secret Service sharpshooters. The bullets killed rallygoer Corey Comperatore, seriously injured two others and wounded Trump in his right ear.

Lawmakers from both parties said the panel’s work would transcend political divisions to establish what happened and give the public an accounting they could trust.

“We’re in the midst of an election cycle right now, and all of us are going to have those tough debates,” Crow said. “But in the United States of America, you do not get to attempt to assassinate our elected officials and our candidates. It’s unacceptable. And we are standing here in a bipartisan way to send the message that we won’t tolerate it.”

Four of the seven Republican members of the panel missed the tour: Reps. Mark Green (Tenn.), Mike Waltz (Fla.), Clay Higgins (La.) and Pat Fallon (Tex.). Their absence was not explained at the news conference.

Along with Kelly, GOP Reps. David Joyce (Ohio) and Laurel Lee (Fla.) were there,as well as Democrats Crow and Reps. Lou Correa (Calif.), Madeleine Dean (Pa.), Chrissy Houlahan (Pa.), Glenn Ivey (Md.) and Jared Moskowitz (Fla.).

“It is so important that this task force has the opportunity to do what we did here, to actually walk these grounds, to see this area, to get an understanding of the physical space and where this security shortcoming took place,” Lee said. “And I’ll tell you, for many of us, it raises more questions than we came here with today.”

Panel members declined to answer questions about preliminary findings they might have. Asked about earlier comments made by Waltz, who told the New York Post last week that he was skeptical of reports that Crooks acted alone, Moskowitz said it was “too early to make that determination.”

“I don’t think anyone on the task force has seen any hard evidence that would suggest that would be the case,” the lawmaker said.

Anthony Guglielmi, a spokesperson for the U.S. Secret Service, said the agency is fully cooperating with oversight efforts by the House congressional task force as well as the Department of Homeland Security’s independent review panel, the DHS Office of the Inspector General and the FBI.

“Our desire to learn from this failure and ensure it never happens again is unwavering and we welcome any and all efforts towards that end,” Guglielmi said in a statement.

The panel has said its primary goals are to ensure accountability, prevent future security failures and investigate the communications breakdowns between the Secret Service and other law enforcement agencies that enabled an armed gunman to access the roof and nearly kill the former president.

House lawmakers have made clear they want decisive action in response to the security failures.

Late last week, just before Secret Service officials briefed lawmakers on their investigation of the assassination attempt, the agency headquarters notified five agents involved in the Butler rally that they were being asked to work from home on “nonoperational duties,” according to two people familiar with the action who spoke on the condition of anonymity to discuss it.

The five included three agents and the top boss from the Secret Service’s Pittsburgh field office, which took the lead in crafting or overseeing a security plan for Trump’s July 13 rally in Butler, and also an agent on Trump’s security detail who visited Butler ahead of the visit to help with that plan, the people said.

The five agents were told to telework, which is not a disciplinary action and does not involve any finding of possible wrongdoing, the people said.

Asked Friday why these employees were instructed to telework, Guglielmi said the Secret Service’s “mission assurance review is progressing, and we are examining the processes, procedures and factors that led to this operational failure.”

“The U.S. Secret Service holds our personnel to the highest professional standards, and any identified and substantiated violations of policy will be investigated by the Office of Professional Responsibility for potential disciplinary action. Given this is a personnel matter, we are not in a position to comment further,” Guglielmi said in a statement.

Jacqueline Alemany contributed to this report