Delta Air Lines is drastically cutting back on flights amid the coronavirus pandemic, sidelining 300 of its planes.

In an internal memo to employees, Delta CEO Ed Bastian said that the move was "the largest capacity reduction in Delta’s history" including after the Sept. 11, 2001, attacks.

"Demand for travel is declining at an accelerated pace daily, driving an unprecedented revenue impact. Cancellations are rising dramatically with net bookings now negative for travel over the next four weeks," Bastian said in the memo. "To put that in perspective, we’re currently seeing more cancellations than new bookings over the next month."

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With multiple countries, including the United States, imposing tight travel restrictions because of the spread of the virus, airline companies have been hit hard.

Notably, Delta will stop all flights to continental Europe for the next 30 days, though it will continue service to London. On Wednesday, President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE announced a ban on travel from all European countries except for the U.K.

Additionally, Delta is implementing an immediate hiring freeze and offering voluntary short-term, unpaid leave for employees. Bastian is forgoing his salary for the next six months in an attempt to stem the hemorrhaging of money from the company.

More than 135,000 worldwide have been infected by COVID-19. In the U.S., there have been more than 1,700 cases of the virus with at least 40 deaths. Dozens of states and Washington, D.C., have issued emergency declarations and several states have canceled K-12 schools for the coming weeks.