Friday brings a big worry for Twitter employees, who keep their fingers crossed over growing uncertainty over their existence in the company. 

The social media company said in an email to staff that it will alert them by 9 a.m. Pacific time on Friday (12 p.m. EDT/1600 GMT) about staff cuts. There is a growing fear that 50% of Twitter's headcount may be trimmed. Several media reports also fuelled speculation that the number could be as staggering as 75%.

As many as 7,500 employees from San Francisco to Singapore fear job cuts that were planned to hit about half of the staff, according to current and former employees and message board posts.

Elon Musk will tell employees by email on Friday about whether they have been laid off, temporarily closing its offices and preventing staff access, following a week of uncertainty about the company's future under the new him.

"In an effort to place Twitter on a healthy path, we will go through the difficult process of reducing our global workforce on Friday," said the email sent on Thursday to employees.

Twitter said its offices will be temporarily closed and all badge access will be suspended in order "to help ensure the safety of each employee as well as Twitter systems and customer data."

The social media platform said Twitter employees who are not affected by the layoffs will be notified via their work email addresses.

Twitter did not immediately respond to a request for comment.

Shortly after the email landed in Twitter employee inboxes, hundreds of people flooded the company's Slack channels to say goodbye, two employees told Reuters. Someone invited Musk to join the channel, the sources said.