ODESSA, Texas — Authorities say the gunman in a West Texas rampage was fired from his job and called both police and the FBI before the mass shooting began.

Odessa Police Chief Michael Gerke said Monday that 36-year-old Seth Aaron Ator had been fired over the weekend from Journey Oil Field Services. He said both Ator and the company called 911 after being fired Saturday but that Ator was gone by the time police showed up. FBI special agent Christopher Combs says Ator's statements on the FBI tip line were "rambling."

Ator was stopped 15 minutes later by a Texas state trooper on an interstate for failing to signal a lane change. Authorities say Ator opened fire on the troopers and fled, shooting at random passers-by and vehicles.

FBI special agent Christopher Combs said Ator "was on a long spiral down" before he was fired. He described where the gunman lived as "a strange residence" and that the condition "reflect what his mental state was going into this."

Police gunned down Ator at a movie theater in Odessa to end the chase.

Republican Gov. Greg Abbott said Monday that the gunman's criminal history means "we must keep guns out of criminals' hands."

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Abbott's tweet Monday is similar to his comments that followed another mass shooting in El Paso last month, when the governor said firearms must be kept out of the hands of "deranged killers." But Abbott, an avid gun rights supporter, has been noncommittal on tightening gun laws in Texas.

Abbott tweeted that Ator failed a previous gun background check and didn't go through one for the weapon he used in Odessa. But Abbott didn't elaborate on when Ator failed the background check or the reasons why.

His spokesman referred questions to the Texas Department of Public Safety, which didn't immediately respond to requests for comment.