The head of Twitter Inc.’s crypto development team has left the company, part of a mass exodus of employees since new owner Elon Musk issued a blanket ultimatum to staff.

She wasn’t the only exit from Twitter’s crypto unit that day, with Hamdi Allam, a senior software engineer on the project, also posting a tweet to say he’d left the business.

Earlier on Thursday, so many employees had either decided to leave the firm or been dismissed that Twitter abruptly shuttered its offices. Musk had told staff to either accept his proposed “hardcore” work environment or leave, though in the final hours before the deadline, he tried to convince some key executives to stay.