Hours after he was fired from his trucking job and 15 minutes after he called the FBI tip line, Ator was pulled over in a sedan by Texas state troopers on Interstate 20 in Midland for failing to use a turn signal, police said.
Armed with an AR-type rifle, Ator fired out the back window of his gold-colored car, wounding one trooper. Then he drove away spraying gunfire indiscriminately, the Texas Department of Public Safety said.
At one point, Ator abandoned his car and hijacked a U.S. postal van, mortally wounding the letter carrier, identified by officials as Mary Grandos, 29.
He shot seven people to death, leaving behind a trail of 15 crime scenes with 23 other people wounded in the rampage, officials said.
Three police officers were shot and wounded - one from Midland, one from Odessa and one state trooper - all in stable condition at hospitals.
Ator was later cornered by officers in the parking lot of a cinema complex in Odessa where he was shot and killed.
The FBI has scoured Ators home, Christopher Combs, special agent in charge of the FBI office in San Antonio, told a news conference on Monday.
I can tell you the conditions reflect what we believe his mental state was going into this, Combs said.
He was on a long spiral of going down. He didnt wake up Saturday morning and walk into his company and then it happened. He went into that company in trouble. Hes probably been in trouble for a while, Combs said.
The rampage came about a month after a gunman from the Dallas area killed 22 people on Aug. 3 at a Walmart store about 255 miles (410 km) west of Midland in El Paso, Texas.