In a massive setback for Twitter, hundreds of employees have quit the company, after new owner Elon Musk’s ultimatum that staffers sign up for “long hours at high intensity,” or leave the company with three months of severance pay.

The departures include many engineers responsible for fixing bugs and preventing service outages, raising questions about the stability of the platform amid the loss of employees, according to a Reuters report.

On the platform Thursday evening, where #RIPTwitter was the top trend worldwide, users wrote what they feared might be their last posts, offering apprehensive goodbyes and listing the other social media platforms where they can still be found, according to a CNN report.

Salute emojis and farewell messages flooded the company’s internal chat groups as a large number of employees decided to leave, Twitter closed its offices till Monday to avoid confusion over which people still have access to the company property, according to a Bloomberg report. 

The billionaire had earlier announced plans to fire about 3,700 people which amounted to 50% of the workforce at the time.

Musk took to Twitter late on Thursday and said that he was not worried about resignations as “the best people are staying.”

He was reported to be meeting some top employees to try and convince them to stay, said one current employee and a recently departed employee who is in touch with Twitter colleagues.

“And we just hit another all time high in Twitter usage…”, he added in a tweet.

The Tesla owner has claimed that since his $44 billion buyout last month, Twitter could face bankruptcy if it doesn’t start generating more cash. So far, Musk has told employees to prepare for 80-hour weeks, no free food and made several changes to the company’s work-from-home policy.