News and media company CNN fired three of its employees for coming to work unvaccinated. CNN chief Jeff Zucker informed the staff of the termination of the three employees through a memo sent Thursday.

Zucker said the employees had violated the company's mandate that all workers must be vaccinated if they enter any of its offices or when they are in contact with other workers. Zucker warned in the memo that the company had a zero-tolerance policy on the matter.

CNN did not provide any further details of the terminations, including the names of those who were fired and where they were based. CNN had offices across the world, and most are already open to workers on a voluntary basis.

Under the company's "no vaccine, no entry" policy, proof of vaccination has been left to the honor system. Zucker said the system might change in the coming weeks in light of the recent incident. He said the company's parent, WarnerMedia, may soon require proof of vaccination for all office employees.

Major companies such as Netflix and Disney have already issued strict "no vaccine, no entry" policies for most workers. Disney, which implemented the policy last week, ordered all salaried and non-union hourly employees working in the U.S. to show proof of their vaccination.

CNN currently requires workers to wear masks at all times in some of its offices, including those in Atlanta, Los Angeles, and Washington, except when they are eating, drinking, or are alone in an enclosed space. Zucker said that workers should do what feels comfortable to them even in offices without any mask mandate.

Apart from announcing the terminations, the memo also announced the postponement of the company's plan to have everyone return to their offices this coming Sept. 7. The memo informed employees that the return-to-office order had been postponed to mid-October. The move is similar to decisions made by other companies given the recent rise in COVID-19 cases.

Zucker said the initial date set for employees to return to their offices "no longer feels appropriate." He reminded workers that the date would remain flexible given the current situation and the uncertainties involved.