The incident began when San Bernardino County sheriff's deputies responding to a stolen car report approached a vehicle on the fourth level of the casino's parking structure, officials said.
Shots were fired and the persons in the car attempted to drive off, making it only to the third level.
They were taken into custody and transported to a local hospital.
No further details were immediately available.
The San Manuel Indian Bingo & Casino remained open.
"The Tribe and Casino do our utmost to ensure that our patrons and employees are in a safe environment when they visit the community and we are working with the Sheriff's Office tonight as well," casino officials said.