It happened at around 5:30pm at Nashville International Airport. A tire had either blown or wheel collapsed. Three ambulances responded as a precaution.
ABC News has learned that three passengers from the flight were admitted to the hospital for minor injuries. The hospital expects to release all three passengers by the end of the night.
The FAA released a statement tonight, which reads, "Southwest Airlines 31, a Boeing 737 aircraft, rolled off a taxiway into the grass and got stuck while taxiing to its gate at Nashville International Airport at 5:30 pm Central Time. Passengers left the aircraft via stairs and were bussed to the terminal. The flight just landed from Houston Hobby Airport. The FAA is investigating."