One of Britain’s biggest holiday operators and airline, Thomas Cook has “ceased trading with immediate effect”, the UK Civil Aviation Authority said on Monday morning.

“All Thomas Cook bookings, including flights and holidays have now been cancelled,” the authority said.

Peter Fankhauser, the chief executive of Thomas Cook , said the tour operator’s collapse was a “matter of profound regret”.

He also apologized to the company’s millions of customers, and thousands of employees. It is believed that around 150, 000 people are expected to be affected by the cancelled flights.

“The government is working with the UK Civil Aviation Authority (CAA) to help passengers return to the UK,” a government statement said.

The group’s four airlines will be grounded and its 12,000 employees in 16 countries as well 9,000 in the UK, are expected to be losing their jobs, due to insolvency.

The collapse of the iconic 178-year-old British tour operator came, due to financial difficulties and failure to secure a deal of around £1.1 billion ($1.37 billion).