The revelation raises questions about whether other measures could have been taken to stop the 20-year-old gunman before he fired at the former president.<\/p>\n\n\n\n
Before a would-be assassin took aim at Donald Trump<\/a> during a campaign rally in Pennsylvania on Saturday, local police officers notified the former president\u2019s Secret Service detail that they were looking for a suspicious person in the area, a U.S. official told NBC News.<\/p>\n\n\n\n The suspicious person, later identified as Thomas Crooks<\/a>, 20, was first flagged to local police officers by rallygoers on their way into the event. The attendees reported they saw Crooks pacing and behaving strangely near the magnetometers, four officials told NBC News.<\/p>\n\n\n\n Local police officers began pursuing Crooks on foot, the officials said. During the pursuit, the U.S. official said, local police told the Secret Service they were looking for a suspicious person near the event.<\/p>\n\n\n\n It is not clear what time the Secret Service was notified and whether it was before Trump took the stage on the grounds of the Butler Farm Show, a venue roughly 36 miles north of Pittsburgh. The U.S. official said the Secret Service was told of a suspicious person before local police discovered Crooks on the roof of a nearby glass research company\u2019s building. That discovery occurred shortly before Crooks opened fire, according to two law enforcement sources.<\/p>\n\n\n\n The timing raises questions about whether other measures could have been taken to stop Crooks.<\/p>\n\n\n\n In the wake of the shooting, a Secret Service spokesman said the location of the roof fell outside the Secret Service\u2019s central security perimeter and was the primary responsibility of local law enforcement. The spokesman said it is common for the Secret Service to coordinate with local law enforcement agencies.<\/p>\n\n\n\n Current and former Secret Service officials told NBC News that, ultimately, responsibility for the security of the agency\u2019s protectees lies with <\/strong>the <\/strong>Secret Service. The former officials said the agency identified the roof where Crooks fired his rifle<\/a> toward Trump as a potential vulnerability before Trump took the stage.<\/p>\n\n\n\n Two former Secret Service agents said the agency could have deployed plainclothes countersurveillance agents to stop the gunman.<\/p>\n\n\n\n Anthony Guglielmi, a spokesperson for the Secret Service, said an independent review panel, announced Monday, will ultimately determine what led to the failure to prevent the assassination attempt. <\/p>\n\n\n\n \u201cDirector Kimberly Cheatle has been working with the secretary [of homeland security] and the White House on the development of the independent review panel,\u201d Guglielmi said. \u201cShe will ensure they have the necessary authority and ability to review the entirety of the incident including planning, resourcing and staffing.\u201d<\/p>\n\n\n\n The Secret Service did not immediately respond to questions about the timeline of when they were notified of the threat. <\/p>\n\n\n\n Top lawmakers in Congress are demanding answers<\/a> about the assassination attempt, requesting briefings and planning investigations. House Speaker Mike Johnson, R-La., said Sunday on NBC\u2019s \u201cTODAY\u201d show that \u201cthe American people need to know and deserve to know\u201d about potential lapses in security.<\/p>\n\n\n\n The revelations about how law enforcement communicated before the shooting come amid growing evidence that at least half a dozen people who attended the rally were pointing to the gunman while he was on the roof getting in position to shoot, trying to alert law enforcement and fellow rallygoers of the imminent danger. <\/p>\n\n\n\n The gunman was crouched on the roof for at least two minutes before Trump was struck, according to an NBC News review of video clips. Videos posted to social media and attendees\u2019 interviews with journalists show the mounting panic people felt as they understood the potential threat. <\/p>\n\n\n\n One 52-second video shows a group of rallygoers outside the perimeter of the open-air venue loudly announcing the gunman\u2019s presence.<\/p>\n\n\n\n \u201cThere he is, right there,\u201d the man who apparently recorded the video says as he points upward, a blurry finger briefly covering the lens. \u201cRight there, see him? He\u2019s laying down, see him?\u201d<\/p>\n\n\n\n Seconds later, someone off-camera can be heard shouting what sounds like a warning to police: \u201cOfficer!\u201d<\/p>\n\n\n\n Trump can be heard on loudspeakers talking about \u201cdangerous people\u201d and \u201ccriminals\u201d coming through the southern U.S. border as a woman yells: \u201cHe\u2019s on the roof!\u201d The woman keeps yelling: \u201cHe\u2019s right here! He\u2019s right on the roof!\u201d Then the video ends.<\/p>\n\n\n\n Anthony Cangelosi, a former Secret Service and homeland security agent who is now an adjunct lecturer at John Jay College of Criminal Justice in New York, said one key question will be what happened in the minutes after rallygoers warned police about Crooks. <\/p>\n\n\n\n \u201cThere needed to be clear communication to counter-snipers after the kid was spotted,\u201d Cangelosi said. \u201cBut was there communication between police officers and Secret Service? These are answers we need to find out.\u201d<\/p>\n\n\n\n In another video posted on social media<\/a>, Trump can be heard talking about border security statistics displayed on a screen as some attendees start yelling: \u201cHe\u2019s got a gun!\u201d <\/p>\n\n\n\n