(Reuters) - An unidentified Kansas City Chiefs player died from a self-inflicted gunshot wound at the team facility on Saturday, the National Football League reported on its website.
NFL.com said Kansas City Police were also investigating an another death related to the incident at Arrowhead Stadium.
Local media described the incident as a murder-suicide.
Television reported the player shot and killed and his girlfriend then drove himself to the team's practice ground and committed suicide.
The player was not named but the Chiefs released a brief statement confirming an investigation was underway.
"We can confirm that there was an incident at Arrowhead earlier this morning," it said. "We are co-operating with authorities in their investigation."
The Chiefs have won just one of 11 games this season, the worst record in NFL. They were due to play the Carolina Panthers on Sunday.
(Reporting by Julian Linden, editing by Ed Osmond)