Twitter employees have been told that all office buildings have been temporarily closed – with more staff thought to be leaving the social media firm.
The managing editor of the tech site Platformer, Zoe Schiffer, tweeted that employees were not given details as to why the offices had been temporarily closed until Monday 21 November.
However in a follow up tweet, she said: “We’re hearing this is because Elon Musk and his team are terrified employees are going to sabotage the company. Also, they’re still trying to figure out which Twitter workers they need to cut access for.”
It comes as a fresh wave of Twitter employees are reportedly leaving the company following an ultimatum from new owner Elon Musk that staff sign up for “long hours at high intensity”, or leave.
Mr Musk has not publicly commented on these latest reports.
The Tesla boss’s ultimatum signals another move in his shake-up of Twitter, following his $44bn takeover of the social media platform last month.
On Wednesday, Mr Musk emailed Twitter employees that they had until Thursday to decide if they wanted to stay on at the company to work tough hours or take a severance package of three months’ pay.
He said to “build a breakthrough Twitter 2.0” the company needed to be “extremely hardcore”.
The world’s richest man warned that employees who didn’t click on a link confirming “you want to be part of the new Twitter” by Thursday 5pm New York time, would be considered to have quit.
In a video posted online, a group of people who claimed to be Twitter employees counted down the seconds, saying they were “about to be fired”.
But in an email to staff on Thursday, he softened his earlier tone, writing that “all that is required for approval is that your manager takes responsibility for ensuring you are making an excellent contribution”.
Workers would also be expected to have “in-person meetings with your colleagues on a reasonable cadence, ideally weekly, but not less than once per month”.
Mr Musk tweeted that he was not worried about resignations as “the best people are staying”, adding: “And we just hit another all time high in Twitter usage… Let that sink in…”
He then proceeded to post a couple of bizarre tweets, including a skull and crossbones emoji.
This was followed with a post appearing to show a photo of a freshly dug grave at a funeral, with a Twitter logo on the epitaph and the same covering the face of a person dressed in black kneeling down next to the gravestone, sticking their two fingers up.
Twitter staffers have repeatedly posted the salute emoji online, in what has become a symbol of solidarity that someone has left the company.
Mr Musk’s acquisition has seen drastic change at Twitter, including the dismissal of the company’s board of directors and top executives, the abolition of remote working and culling half the workforce.
He also announced that Twitter will charge users $8 a month for blue check marks to verify the authenticity of a user’s account.