A gunman lay in wait outside Oklahoma City's main airport before shooting and killing a Southwest Airlines employee in a premeditated attack that resulted in a lockdown of the area and flight being diverted.
Michael Winchester, 52, was shot while walking between a crowded terminal and the airport employee parking area.
The unidentified suspect was later found dead in a pick-up truck in public parking garage overlooking the scene. Police said the suspect appeared to die of a self-inflicted gunshot wound.
Oklahoma City police captain Paco Balderrama said the shooter apparently knew the victim's schedule and routine.
"This individual went there and waited for the employee to either be coming or going to take this opportunity," Balderrama said. He wouldn't say conclusively that it was a "sniper-type" attack.
The 1pm shooting set off a scramble at Will Rogers World 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.
Winchester was a former University of Oklahoma football player whose son James is a player for the Kansas City Chiefs.
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 pick-up truck on the second floor of a public parking garage was dead, officers gave an all-clear.
The airport handles between 7000 and 8000 passengers daily.
Video from a television station helicopter showed what appeared to be a pool of blood about 30 metres from the airport's employee parking area.
Balderrama initially said police had received reports of a possible second victim, but no one was found.