In an email to staff members obtained by NBC News, Twitter said it would "reduce our global workforce on Friday."
Twitter will lay off staff members, he said in an email obtained by NBC News.
In an email sent late Thursday, Twitter said it would notify staff via email about their work.
"We recognize that this will impact a number of individuals who have made valuable contributions to Twitter, but this action is unfortunately necessary to ensure the company's success moving forward," the email said.
It has been widely reported that Musk plans to slash the salaries of the company's 7,500 people after he completed his $44 billion acquisition last weekend. He immediately fired CEO Parag Agrawal, as well as Twitter's chief financial officer and head of law, public policy and trust and safety after taking over the company.
A Twitter employee said Thursday's email was the first a communications staff member had received from Twitter since the Oct. 27 acquisition.
"It's a complete mess, the house is destroyed, everyone is looking at this email," the employee said.
According to an email from Twitter, staff members will be notified either via their company email account - if they still have a job - or their personal email account if "their work is affected."
The company said staff were being reduced in "an effort to put Twitter on a healthy path."
Worries about layoffs began to surface before the purchase deal was completed, but Twitter's general counsel urged employees not to dwell on the rumors before Musk took ownership.
Some Twitter employees have expressed a desire to be laid off and get severance pay, and some worry that disagreeing with Musk could mean job loss and an exit package.
"At the end of this nightmare, I'd rather get a cash prize," said a Twitter employee.
Meanwhile, Musk has sought to reassure advertisers, saying in a post on Twitter that the platform would not be a "free-for-all hell sight." He also told the European Union he plans to comply with the Digital Services Act, which penalizes companies if they don't control illegal content, Reuters reported Monday.
Musk has also promised to relax rules about what types of speech are allowed, sparking concerns that the changes could turn users and advertisers away. General Motors announced it would suspend its advertising on the platform.
He also said he planned to set up a content moderation board that would cover "very diverse viewpoints"; so far no change.
Reports suggest that hate speech spiked in the days of Musk's opening of ownership of the site. Musk himself posted a link to a baseless anti-LGBTQ conspiracy theory Sunday about the attack on Paul Pelosi, husband of House Speaker Nancy Pelosi, D-Calif. Musk deleted the tweet.
It was among nearly two dozen tweets Musk posted last weekend, some of which offered additional clarity on what the site would look like under his leadership.