Australian airline Qantas said that a hacker made off with a trove of customers’ personal data including passenger names, emails, phone numbers, birth dates and frequent flyer numbers.

Australian airline Qantas says a data hack on Monday exposed the personal information of six million customers and it expects the amount stolen to be “significant.”

Australian airline giant Qantas said on Wednesday it experienced a data breach that compromised the personal information of at least six million passengers.