Bystanders warned police of the presence of former President Donald Trump’s attempted assassin nearly 90 seconds before the shooting, according to a video taken right before the harrowing shooting.

The video shared on social media showed bystanders frantically trying to alert police of the presence of the believed shooter, Thomas Matthew Crooks, 20, as he took up position on the roof of a building with a view of Trump. At least one Butler Township police officer was warned.

One of the officers can be seen looking up at the roof where the suspect was.

Ben Maser, who was seen in the video clip, told the Washington Post that he had warned police two separate times to no avail. In response to both alerts, the officer he was warning “didn’t say anything,” Maser claimed. Video showed bystanders trying to alert police of the shooter for at least 86 seconds before the shooting started, an analysis by the newspaper found.

Not only were police warned by the public in the immediate lead-up to the shooting, but a report from WPXI, a local Pittsburgh outlet, said the suspect had been monitored nearly a half hour earlier.

Multiple law enforcement sources told the outlet that the shooter was spotted 30 minutes before the shooting. A source told the outlet that Beaver County’s Emergency Services Unit noted Crooks as a suspicious person while he was at his position on the roof and took a picture of him.

It wasn’t clear if Crooks was carrying a gun when the image was taken.

Before the roof picture was taken, another law enforcement officer reportedly saw Crooks on the ground, reported what they saw, and took a picture too. The Secret Service and police in charge of security at the event have faced heavy scrutiny following the shooting.

The Washington Examiner reached out to the Secret Service for comment.

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Trump narrowly survived the first serious assassination attempt against a president or former president in over 40 years, turning his head at the last moment so the bullet only grazed his ear.

One bystander, former volunteer fire chief Corey Comperatore, was shot in the head while shielding his family. He was killed, while two others were seriously wounded.