Twitter has told employees that the company's office buildings will be temporarily closed, effective immediately.
In a message seen by the BBC, workers were told that the offices would reopen on Monday 21 November.
It did not give a reason for the move.
The announcement comes amid reports that large numbers of staff were quitting after new owner Elon Musk called on them to sign up for "long hours at high intensity" or leave.
The message went on to say: "Please continue to comply with company policy by refraining from discussing confidential company information on social media, with the press or elsewhere."
