The gunman who killed seven people and left 25 others injured in West Texas on Saturday had just been fired from the job and called the FBI before the massacre began, the investigative agency said on Monday.
At a press conference, FBI special agent in charge Christopher Combs said that the gunman, identified as 36-year old Seth Ator, had been "on a long spiral of going down" and was in a "distressed mental state" when he showed up at work on that day, reported CNN.
Without elaborating, Combs said that the place where Ator lived was "a very strange residence" and that the conditions "reflected what, we believe, his mental state was (when) going into this".
The chain of events leading to the shooting began after a Department of Public Safety officer pulled over Ator's vehicle on an interstate highway on Saturday afternoon. He then shot the officer, took off, and started shooting randomly.
The FBI special agent said that the shooting did not happen because the man was fired from the job, since he was already enraged when he showed up at work that day.
The police have said that that the suspect used an AR-type weapon in the shooting, albeit the investigation is still underway as to how he obtained the firearm. The ATF, the FBI and the DPS are "aggressively following up on" the source that supplied him the weapon.
The incident has rekindled the debate over gun laws in the United States, which has witnessed several incidences of mass-shooting in the past few months, including the deadly El-Paso attack in the state of Texas.