Twitter sacked half of its 7,500-strong staff on Friday as new owner Elon Musk launched his major overhaul of the troubled company just a week after his blockbuster takeover.
An internal document seen by AFP said "roughly 50 percent" of employees were impacted and would be denied access to company computers and email on an immediate basis.
Workers around the world were shown the door and took to Twitter to vent their frustration or disbelief and say goodbye to one of Silicon Valley's most iconic companies.
"Woke up to the news that my time working at Twitter has come to an end. I am heartbroken. I am in denial," said Michele Austin, Twitter's director of public policy for the United States and Canada.
"Regarding Twitter's reduction in force, unfortunately there is no choice when the company is losing over $4M/day," Musk tweeted Friday evening in his first comment on the subject, 24 hours after the company's initial email notifying employees of forthcoming layoffs.
Ahead of the layoffs, Twitter closed access to its offices worldwide, asking employees to stay at home to await news of their fate through an email.
"It's a pretty inhumane way to treat people. It seems like a mercenary effort, they're trying to save money at all cost," said one dismissed employee who spoke on the condition of anonymity.
The cull is part of Musk's push to find ways to pay for the mammoth $44 billion deal for which he took on billions of dollars in debt and sold $15.5 billion worth of shares in Tesla, his electric car company.
Company sources said that Musk's teams were imposing a furious pace on the remaining employees, bringing in Tesla developers to oversee the work of "Tweeps," the inhouse name for Twitter workers.
Musk, the Tesla and SpaceX chief, is said to owe $1 billion in annual interest alone to pay for a deal he tried to wiggle out from almost as soon as he made it in April.
Musk has been scrambling to find new ways for Twitter to make money after his mammoth buyout, including an idea to charge users $8 a month for verified accounts.
The moves would help overcome the potential loss of advertisers, Twitter's main source of revenue, with many of the world's top brands putting their ad buys on hold, spooked by Musk's well-known disdain for content controls.