A west Texas man, on a "downward spiral," made "rambling" calls to police and the FBI before embarking on a shooting spree that took the lives of seven innocent bystanders, authorities said Monday.

The killer, 36-year-old Seth Ator, had been fired by his employer, Journey Oil Field Services, on Saturday before he went on his bloody rampage in the neighboring cities of Odessa and Midland, Texas.

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"Right after that firing he called 911 ... and so did his employer," Odessa police chief Michael Gerke told reporters. "And basically they were complaining at each other because they had a disagreement over that firing."

He left his trucking business employer's office before police showed up.

Then the killer called the FBI's national tip line, again went off in nonsensical statements, authorities said.

"It was, frankly, rambling, statements about some of the atrocities that he felt he had gone through," said Christopher Combs, special agent in charge of the FBI's office in San Antonio. "He did not make a threat in that phone call."

In both calls to authorities, Ator did not give any hints he was about to kill seven people, authorities said.

"It's a rambling statement. He rambled a lot in all of his contacts," Gerke said. "No threats."

Seth Ator Texas Department of Public Safety

Pursuing police eventually tracked down Ator and fatally shot him outside a movie theater.

Authorities finished their search of Ator's home on Sunday but are still going over what they found inside.

While the FBI and police stopped well short of explaining the killer's motive, they painted a picture of a man who'd been struggling for a long period of time.

"It's a very strange residence. It's very small. I can tell you the conditions reflect what we believe his mental state was going into this," Combs said.

"He was a long spiral of going down. He didn't wake up Saturday morning and walk into his company and then it happened. He went to that company in trouble, probably been in trouble for a while ... we really need the public's help to reach out to us when they see people in that downward spiral that may be on that road to violence."