NEW YORK (AP) — Employees braced for widespread layoffs at Twitter Friday as new owner Elon Musk overhauls the social platform.

In a letter to employees obtained by multiple media outlets, the company said employees would find out by 9 a.m. PDT (noon EDT) if they had been laid off. The email did not say how many people would lose their jobs.

Some employees tweeted early Friday that they had already lost access to their work accounts. They and others tweeted messages of support using the hashtag #OneTeam. The email to staff said job reductions were “necessary to ensure the company’s success moving forward.”

Twitter’s roughly 7,500 employees have been expecting layoffs since Musk took the helm of the company. Already, the billionaire Tesla CEO has fired top executives, including CEO Parag Agrawal, on his first day as Twitter’s owner.

He also removed the company’s board of directors and installed himself as the sole board member. On Thursday night, many Twitter employees took to Twitter to express support for each other — often simply tweeting blue heart emojis to signify Twitter’s blue bird logo — and salute emojis in replies to each other.

As of Friday, Musk and Twitter had given no public notice of the coming layoffs, according to a spokesperson for California’s Employment Development Department. That’s even though the Worker Adjustment and Retraining Notification statute requires employers with at least 100 workers to disclose layoffs involving 500 or more employees, regardless of whether a company is publicly traded or privately held.

A class action lawsuit was filed Thursday in federal court in San Francisco on behalf of one employee who was laid off and three others who were locked out of their work accounts. It alleges that Twitter intends to lay off more employees and has violated the law by not providing the required notice.

The layoffs come at a tough time for social media companies, as advertisers are scaling back and newcomers — mainly TikTok — are threatening the older class of social media platforms like Twitter and Facebook.

In a tweet sent Friday while employees were learning if they’d lost their jobs, Musk blamed activists for what he described as a “massive drop in revenue” since he took over Twitter late last week. He did not say how much revenue had dropped.

Big companies including General Motors, General Mills and Audi have all paused ads on Twitter due to questions about how it will operate under Musk. Volkswagen Group said Friday it is recommending its brands, which include Skoda, Seat, Cupra, Audi, Lamborghini, Bentley, Porsche and Ducati, pause paid activities until Twitter issues revised brand safety guidelines.

Musk has tried to appease advertisers, but they remain concerned about whether content moderation will remain as stringent and whether staying on Twitter might tarnish their brands.

“Twitter has had a massive drop in revenue, due to activist groups pressuring advertisers, even though nothing has changed with content moderation and we did everything we could to appease the activists,” he tweeted.