Members of a task force investigating the attempted assassination of former president Donald Trump have been left with "more questions than answers" after a visit to the site.
Weeks after the shooting that left one man dead and several others, including Trump, injured, questions remain about how the 20-year-old gunman was able to open fire
The House of Representatives task force, established on July 29, has assumed control over all committee investigations.
Its members were accompanied on their tour by local and state police officials, visiting first the area where Trump took the stage before proceeding to the rooftop site the shooter fired from.
Task force chairman Mike Kelly said the team had "really good people looking for the truth".
He added visiting the scene in Butler, compared to looking at pictures and video, was "the difference between day and night".
"When you're actually here on this surface, when you're walking these grounds, when you're actually going to the building, you're actually up on the roof, looking at where we had people positioned … right away, it's like, 'Okay, I got it,'" he said.
"So for us, the big thing was to be on the ground … be comfortable with the questions we were going to ask."
At least five Secret Service agents have been placed on modified duty and the organisation's then-director Kim Cheatle has resigned in the wake of the shooting.
Ms Cheatle came under intense scrutiny amid questions about how shooter Thomas Matthew Crooks was able to get on top of the building near the rally venue with a rifle.
The rooftop from which Crooks fired was less than 150 metres from the podium. It had been identified as a point of vulnerability days before the rally.
Crooks, who was shot and killed by Secret Service snipers moments after opening fire, appeared to have a clear view of Trump from the roof.
Colorado Democrat and special forces veteran Jason Crow, a former Army Ranger also on the task force, said it was a "fundamental" principle in the military to "secure the high ground".
"Or you always have eyes on the high ground," he said.
"So I definitely took note today that there are a lot of lines of sight that appear to have been unsecured.
"Certainly at this point [there are] a lot more questions than answers."
[jason crow] He declined to comment on who the committee was specifically planning to interview as part of their investigation.
The task force, which is made up of both Republican and Democratic representatives, was approved by the House in a bipartisan vote of 416 to 0.
Mr Kelly said: "When you talk to the members of this committee who have done military service, they look at it … and they say, 'How could this not have been prevented?'
"And the burning question [for me] is always going to be, there was knowledge ahead of time that there was a person of suspicion on that roof and armed.
"The key [thing] was, get the former president of the United States off the podium, then there's nothing that has to take place.
"[Corey] Comperatore would be alive today … not only did we lose Mr Comperatore that day, the Crooks family lost their son."
Investigators have so far struggled to understand why Crooks, a nursing facility aide, carried out the attack.
Ms Cheatle, FBI director Christopher Wray and other security officials said in a briefing call with US senators last month they had yet to find a "political or ideological" motive.
They have also not found any indication of any co-conspirators after searching his home, his laptop and two phones.
