Gunman who "executed" Florida Citibank employee was angry about $2,500 debt

Citibank shooter angry over debt killed employee New video shows the gunman crashing through the gates of Citibank's Brandon complex at lunchtime Wednesday, barely missing an employee at a picnic table. Officials say a gunman enraged over a $2,500 debt shot and killed a female worker at sprawling Citibank Center near Tampa Wednesday morning before an armed security guard fatally shot him. Deputies: Gunman drove from Orlando to the Citbank Center corporate campus to carry out ambush The Hillsborough County Sheriff's Office Investigators said Jacob Pearson, 35, targeted the Citibank campus because he was angry over a $2,500 debt collection. (Hillsborough County Sheriff's Office) What we know: Hillsborough County Sheriff's Office investigators said Jacob Pearson, 35, drove from Orlando to the corporate campus, about 90 miles away, after phoning in explicit death threats to a law firm handling collection proceedings for Citibank. Man kills Citibank worker over $2,500 debt: HCSO Jacob Pearson shot and killed Citibank worker LeAnne Selmon at the company's Tampa center Wednesday before a guard fatally shot him. Hillsborough County Sheriff Chad Chronister said deputies rushed to the facility where 3,200 employees work following an urgent warning from onsite security, but gunfire erupted moments after their arrival. Investigators said Pearson crashed his car through a courtyard security gate shortly after noon, got out of his car with a rifle and shot employee LeAnne Selman, 41, three times. Chronister said Pearson's rifle jammed after the three shots and he then retrieved a handgun from his car and again shot Selman, who died. What they're saying: "He was there intent on one purpose, and that purpose was to hunt any human being he could find and kill them," Chronister said. Dig deeper: After shooting Selman, Chronister said Pearson made his way to the cafeteria, sending thousands of terrified employees running for exits or ducking into hiding spots across the campus. Chronister said John Fraley, a Citibank security guard and Marine Corps veteran, tracked Pearson into a men's restroom and opened fire, striking Pearson five times during an exchange of gunfire.  Pearson was transported to Tampa General Hospital where he was pronounced dead. Citibank shooting: Suspect seen ramming fence, going inside building The Hillsborough County Sheriff's Office released new video showing the chaotic moments from on the Citibank campus as the suspect rammed into a fenced-in area and ultimately went inside the facility. It also shows deputies going in to clear the building and getting employees out. Courtesy: Hillsborough County Sheriff's Office. Citibank employees recount evacuation The attack unfolded as many of the 3,200 employees at Citibank's campus in suburban Tampa were eating lunch. Local perspective: One employee, who asked to remain anonymous, was working on the building's third floor when the shooting began. He initially thought it was a fire drill before hearing screams and people shouting about a gunman. He and several coworkers eventually locked themselves inside a small room, where they waited for the situation to end. What they're saying: "All I hear is, ‘gun, gun, he's got a gun, we have to move, we've got to get out here!’ So it was just utter chaos and mayhem," he said. The employee, who has a military background, said he tried to remain calm and help others make safe decisions. "I felt very vulnerable in that moment. You're essentially locked in a small closet with six other people, most of them being women who have never been in a situation or even heard gunfire before, and they're freaking out, and you're trying to be logical and help them through this." Unanswered questions surrounding motive in Citibank shooting What we don't know: Detectives have not determined why Pearson singled out Selman in the courtyard or whether he had targeted specific individuals inside the corporate building. Authorities have not revealed how Pearson obtained the firearms used in the rampage, given that he possessed no prior criminal record. Pearson’s father, Richard Pearson, told The Associated Press that he had never seen an indication that his son was capable of carrying out a violent shooting. Phone records detail threats Pearson made to Citibank The backstory: Investigators said Pearson contacted an attorney's office contracted by Citibank for debt collection after receiving a court summons regarding a $2,500 delinquent payment. The sheriff stated that Pearson issued a graphic warning over the telephone: "Unless you want me to go over there with my AR-15, my bulletproof vest and my insanity, you mf’ing cancel this court case. Do you understand me? They are only an hour and three minutes away, so the last thing you want to do is f with me." Following the call, investigators said the law office alerted Citibank's head of security, a retired Secret Service agent, who immediately initiated emergency measures. Security requested a welfare check from the Orlando Police Department at Pearson's home where he lived with his wife and 7-year-old child, but responding officers discovered he had already departed. Pearson's wife informed Orlando officers that her husband left the house looking visibly angry without disclosing his destination. Citibank security then alerted the Hillsborough County Sheriff's Office, prompting dispatchers to send deputies to protect the corporate center. Citibank: Leanne Selman was "a beloved employee" Leanne Selman had worked for Citibank for nine years in human resources. (Hillsborough County Sheriff's Office) What they're saying: Citibank said Leanne Selman worked as a human resources learning advisor for Citi Security Investigative Services.  She had worked for Citibank for nine years and was "a beloved employee," said Ed Skyler, spokesperson for Citibank parent Citigroup. The sheriff said there was "zero connection" between Selman and her killer. Four employees treated by medical workers Medical workers treated and released four other people hurt during the chaotic mass evacuation. One worker suffered a cut lip, another sustained cuts and bruises from a fall, a third person experienced chest pains, and a pregnant worker went to the hospital as a precaution. Citibank security guard and Marine Corp veteran John Fraley hailed as a hero for stopping gunman What they're saying: Sheriff's officials commended Fraley for preventing further bloodshed as thousands fled the campus grounds. The violence could have been far worse, the sheriff said. Pearson brought 90 rounds of ammunition to the campus, he said, but fired just 15 times before he was stopped by Fraley. "He was there intent on one purpose and that purpose was to hunt any human being he could find and kill," the sheriff said. "Because of the heroic actions of this Citibank security officer, vice president of operations, his reign of terror ended before it even began," said Chronister. "He is an individual that's afforded an opportunity to carry a firearm because the ones who were either previous law enforcement or military and have that training. Citibank empowers them to carry a handgun." The Source: This article includes information from the Hillsborough County Sheriff's Office, The Associated Press, and previous FOX Local reporting. This story was reported from Orlando and Tampa Bay, Crime and Public Safety