INDIANAPOLIS — ATA Airlines shut down operations and stranded thousands of travelers Thursday when an unexpected loss of key charter flights and soaring fuel costs forced the carrier into bankruptcy.

Once the nation's 10th-largest air carrier, ATA entered bankruptcy for the second time in just over three years. The company had more than 2,200 employees, and "virtually all" were told that their jobs were gone, company spokesman Michael Freitag said.

Many passengers learned of the collapse at ticket counters, where advisories were posted in the handful of cities ATA still served. About 10,000 passengers flew ATA each day when operations were shut down, according to the airline. ATA does not have regular flights to Salt Lake City.

ATA was the second carrier to declare bankruptcy in just the past two weeks. Aloha Airlines filed for Chapter 11 bankruptcy protection last month.