Trump supporters seen in chilling video trying to warn police of rooftop gunman moments before shots ring out

Cellphone video taken on Saturday shows panicked Trump rally attendees pointing at shooter Thomas Matthew Crooks and yelling to alert police as he shimmied across a roof and into position minutes before he fired.

Video from the scene appears to show attendees trying to alert authorities to the shooter's presence 86 seconds before Crooks fired.

In other footage taken of the incident, people were seen running from the area about 15 seconds before shots were fired, while others were heard yelling that the man on the roof had a gun.

"Look, they're all pointing," the man shooting the video can be heard saying. "There he is right there. Right there, you see him? He's laying down, you see him? What's happening."

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"He's on the roof," another woman can be heard yelling. "Right here."

Crooks purchased a ladder at a Home Depot, a brief drive from his family home before the rally on Saturday – it is unclear whether he used that ladder to get onto the roof of a building about 410 feet from the main stage where Trump stood, just outside the bounds of the security perimeter established for the former president on the property. 

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There were four counter sniper teams at the rally, including two from the Secret Service and two from local law enforcement. That building Crooks fired from was a "rally point" for one of the local counter sniper teams, according to a federal law enforcement official familiar with the security plans.

A team was stationed in, or near, the building, the source said.

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One of those snipers saw Crooks outside the building looking up at the roof and observing the building before disappearing, a local law enforcement officer told CBS News. He then saw the gunman return to the building, sit down and look at his phone. 

One of the snipers took a picture of Crooks, then saw him looking through a rangefinder minutes before the assassination attempt, per the outlet. He radioed a command post and tried to send the photo up the chain of command before Crooks fired. 

More than a dozen firearms were discovered inside the Crooks family home, NBC News reported, and the shooter's father called police to tell them his AR rifle was missing after the incident. The rifle used in the shooting was purchased legally, and may have belonged to his father.

Officials have said Crooks acted alone in trying to kill Trump but are still investigating. His classmates at Bethel Park High School, where he graduated in 2022, characterized him as a quiet loner who was bullied.