There were early warnings to police. A Secret Service sniper team abruptly changing position. A sudden panic and then — Multiple gunshots fired at the former president. A bullet passing right by his head. One person was killed. Two more were injured. How could such a brazen assault occur at a rally protected by the Secret Service and several other law enforcement agencies? To piece together what happened second by second, The New York Times reviewed dozens of videos and photos and examined audio from the rally. Our analysis shows how a clear threat emerged minutes before the shooting. And how law enforcement failed to protect the former president. “Take a look at what happened.” And those who came to see him. Thousands are attending a weekend rally for Donald Trump at a showground in Butler, Pennsylvania. Behind the stage where Trump will speak, two teams of Secret Service snipers are posted on top of sheds. They’re facing in opposite directions, covering different areas of the rally. The Secret Service is also protecting the area closest to the stage. For areas further away, state and local law enforcement are responsible for security, and they are using this building as a staging area. Snipers are positioned on the second floor. Videos show several police cars parked outside. An hour before the shooting, the suspect is filmed loitering in this area. A local law enforcement official told The Times that around 20 minutes before Trump began speaking, a police officer took a photo of the man who was acting suspicious. The officer circulates the photo among other officers, but loses track of the suspicious man. At 6:05 p.m., Trump begins his speech. It will last just six minutes. Right now, the sharpshooters behind him appear relaxed and are standing upright. At 6:09 p.m., exactly two minutes before Trump is hit, rallygoers start pointing at a man crawling atop this building next to the staging area. It’s the building closest to the rally area. “People, criminals. We have criminals.” As the crowd yells warnings, The Times identified at least one local police officer walking alongside the building. At the same moment this scene plays out, footage captures one of the sniper teams behind Trump turn around and face toward the building. The other sniper team can also be seen looking intently in the same direction. “My guys, take a look at that chart. Take a look at the arrow on the bottom.” As Trump continues his speech, the man continues to crawl across the roof for over a minute. At some point, according to a local official, a police officer is hoisted up to check the roof, but drops when the gunman aims at him. “And look what happened to our country —” Seconds before he opens fire, people at the rally’s perimeter see he’s holding a weapon and begin to run. One of the snipers drops his binoculars. The other grabs his gun. Within seconds, three shots ring out — “Take a look at what happened” — followed by a volley of several more. Video analysis shows the first bullet hitting the bleachers to the right of the stage. Trump is hit. Secret Service agents swarm him. Seconds later, a rifle shot is heard by the building. The gunman is shot. So where did the bullet come from? “He’s on top of the roof.” “Don’t go over there.” Audio analysis of this video by an acoustic expert at Montana State University found that the distance from the camera to the sniper who took the fatal shot was roughly 175 yards. This matches the distance from the camera to the southern sniper team, indicating one of these officers likely killed the suspected gunman. We also know from aerial imagery of the area that a tree blocked the northern sniper team’s line of sight to the gunman. But the southern team had a clearer view. Back at the rally, one minute after Trump is hit, the Secret Service say the shooter is down. As they moved to take Trump from the stage, he orders them to stop. And mouths the word “fight” to his supporters. On the bleachers behind him, three people have been struck by bullets. A volunteer firefighter named Corey Comperatore was killed by a shot to the head. Two other rallygoers were critically injured. A federal investigation has been opened into security failures at the rally, and there are still many unanswered questions about the gunman’s motives and movements before the shooting. But our analysis raises another question: one the Secret Service wouldn’t comment on. Why the former president was allowed to remain on stage when the threat had emerged minutes before the attempt on his life.