OKLAHOMA CITY (WTVD) -- Oklahoma City police investigators worked to piece together why a man waited to gun down an airline employee outside Will Rogers World Airport on Tuesday in an ambush that forced hundreds of travelers to take shelter and prompted authorities to shut down the state's busiest airport for hours.
Police later discovered the suspected shooter dead from an apparently self-inflicted gunshot wound inside a pickup truck in a parking garage near where they believe he waited, watching airport employees come and go before shooting and killing Michael Winchester, 52, a Southwest Airlines employee.
Winchester - whose address is listed as Washington, Oklahoma, about 35 miles south of the airport - was a former University of Oklahoma football player whose son James is a player for the Kansas City Chiefs.
"We do believe this was a premeditated act against the victim," said Oklahoma City Police Capt. Paco Balderrama. "This was not random, and obviously the investigation is ongoing in reference to the other details."
Balderrama said late Tuesday that investigators hadn't positively identified the shooter, but said the man apparently knew Winchester's schedule and routine and that the two men likely knew one another.
"It's too early in the investigation to figure out the exact motive," Balderrama said.
The 1 p.m. shooting set off a scramble at the airport, with police immediately closing the sprawling complex and asking passengers inside to seek cover.
They diverted incoming flights and refused to give already-loaded aircraft permission to leave. There were concerns the gunman might have entered the terminal and mingled among passengers or employees.
"We have a heightened level of security all the time. These people have access to aircraft so we're very concerned about that," airport spokeswoman Karen Carney said.
Southwest Airlines canceled flights out of the city for the remainder of the day even though the rest of the terminal reopened.
Hundreds of people were stranded inside the terminal for more than three hours before officers began letting them leave slowly. Carney said about 300 people were held on aircraft away from the terminal after their planes landed ahead of a ground stop.
Once police determined that a suspect found in a red pickup truck on the second floor of a public parking garage was dead, officers gave an all-clear.
The airport handles between 7,000 and 8,000 passengers daily for Alaska, Delta, Southwest and United airlines and has a separate terminal that serves as a transfer center for federal inmates. A jet carrying inmates to the transfer site was allowed to land while the rest of the airport was shuttered.
Video from a television station helicopter showed what appeared to be a pool of blood about 100 feet from the airport's employee parking area - and about 100 yards from the airport's ticket counters and departure area.
While airports have high security, it wasn't immediately known whether surveillance cameras might show the shooting, Balderrama said.
Balderrama initially said police had received reports of a possible second victim, but no one was found.
Police found the suspect's truck in the garage about three hours after the shooting and determined that someone was inside. They were not sure whether he was dead or alive. After about 75 minutes, using a robot, officers determined the suspect was dead.
A number of inbound flights were diverted to other airports after Will Rogers suspended operations. Southwest redirected one flight back to Dallas while a Las Vegas to Houston flight that stops in Oklahoma City went to Amarillo, Texas, instead. Two commercial flights from Chicago's O'Hare International Airport were directed to Tulsa, about 100 miles away.
Michael Winchester was a punter on the University of Oklahoma's 1985 national championship team.
"Our hearts are truly heavy for the entire Winchester Family. Mike was a former Sooner student athlete as was his son James/daughter Carolyn," the school's athletic director, Joe Castiglione, tweeted Tuesday afternoon. He added "daughter Becca was also a student athlete. Please keep this beautiful family in your prayers" in a later tweet.
The Associated Press contributed to this report