OKLAHOMA CITY - Police said a suspect in the fatal shooting of a former University of Oklahoma punter at Will Rogers World Airport in Oklahoma City has been found dead in a pickup truck in an airport parking garage on Tuesday.

Police Capt. Paco Balderrama said the suspect appears to have died of a self-inflicted gunshot wound. He has not yet been identified.

Michael Winchester, 52, was shot shortly before 1 p.m. Tuesday. He died after being taken to a hospital.

Winchester was a punter for OU from 1984 to 1986. He was the father of Kansas City Chiefs long snapper James Winchester, who also played at OU.

Balderrama said police believe the shooting was a premeditated attack.

Southwest Airlines confirmed Winchester was an employee and they canceled the rest of their departing flights for the day.

Police conducted a sweep of the airport and parking garage but the suspect remains on the loose. FBI agents and tactical teams are also on the scene.

Investigators believe it was an "isolated incident."

The airport remains on lockdown while the investigation continues.

An airport spokesman said via Twitter that all inbound and outbound air traffic has been stopped and police are asking travelers to avoid the area.

Southwest Airlines released the following statement:

"It is with great sorrow that Southwest Airlines confirms that a Southwest Employee who was injured during a shooting incident today at Will Rogers World Airport in Oklahoma City has died from injuries. We continue to work with the local authorities investigating this incident.

"As a result of the police investigation, local flight operations have been halted. We're working to accommodate Customers still in the airport when it was locked down as well as cancelling flights departing from Oklahoma City for the remainder of the day.

"The Southwest Airlines Family is deeply saddened by the passing of our Southwest Family Member, and we extend our heartfelt sympathies and support to his family and Southwest Co-workers at this time."