The incident unfolded at about 2:30 a.m. when a male guest got into a physical confrontation with another person inside the casino's parking garage.
Casino security personnel saw the scuffle and called Puyallup Tribal Police for help.
When tribal police arrived on scene, they stunned the guest with a Taser to bring him under control. He was then handcuffed and placed in a police car.
Shortly afterward, as the man was being transported to the police station, he stopped breathing in the patrol car. Tribal police administered CPR to the man, but he could not be revived.
The man's death is now under investigation by Puyallup Tribal Police. The FBI also has been asked to assist in the investigation, said FBI spokeswoman Ayn Dietrich.
No other information was available about the man, including his name and age.
This is a developing news story. More information will be posted as it becomes available.