Donald Trump has Secret Service snipers to thank for taking out the gunman who apparently tried to assassinate him -- because just a second after he fired ... they took him out from an opposite roof, all of which can now be seen in new video.

This clip -- which was posted by a TikTok user and is now going viral -- shows the shooting from a different angle ... and it's eye-opening on a number of fronts ... 'cause it shows what was going on in the moments leading up to shots ringing at the Butler rally.

As you can see, there are at least 2 Secret Service agents on what appears to be a barn rooftop and they have their weapons out and ready -- seemingly tracking a target from afar.

You can see Trump on the stage just below them ... and as he's finishing a sentence, you can hear at a couple shots ring out -- which clearly came from the gunman -- with DT reacting and touching his ear, with screams from the crowd belting out and people panicking.

Almost instantaneously, you can also see one of the snipers on the roof fire their own weapon ... with the gun rocking due to the recoil. As we know, the gunman was neutralized.

What's interesting ... it appears as if the snipers on the roof might've been aware of the gunman across the way for at least some amount of time, and if that is in fact the case ... that tracks with what an eyewitness claimed -- namely, he flagged the gunman but law enforcement didn't move quickly enough to take out the threat *before* shots could be fired.

The way this guy told it ... cops and at least some Secret Service agents were aware of the gunman on the roof prior to him shooting -- and this witness questioned why they waited so long to do something. It's a fair question ... of course, more answers will trickle out soon.

As we told you ... Trump says he was shot in the ear, and once he was hit and it became clear bullets were flying -- other Secret Service agents on the ground pounced on him ... covering him up and quickly escorting him to a vehicle and out of harm's way.

Trump was defiant as he was being led away -- pumping his fist and getting the crowd to cheer him on. He was clearly bleeding from his ear ... and is said to be in good condition.

Like we said, the gunman was taken out ... but sadly, at least one other rally attendee was killed in the mayhem. At least two others are reported to be critically injured.

DT has spoken out on the shooting ... expressing thanks to law enforcement, while also noting his dismay at the fact this could happen in 2024. The identity of the gunman has yet to be released ... but there are videos/photos circulating purporting to show the aftermath.

The shooting is being investigated as an attempted assassination.