General Motors was stunned this week after employees stormed the offices of the company’s Korean CEO and smashed it up.

In a video posted to YouTube on Thursday, a dozen GM Korea workers entered the CEO’s office and removed furniture, including a desk and conference table. The workers, who were all dressed the same, then destroyed all of the furniture and nearly everything else in the office, leaving it a mess.

According to Bloomberg, which earlier reported on the video, the workers were part of a union that were protesting the company after it withheld bonuses due to financial problems. The union was also calling on the CEO to resign.

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General Motors has been faced with an increasingly challenging Korean market that has turned elsewhere for vehicles. The company reported recently that March sales were down 58% year-over-year after they fell by 48% in February. Late last month, Reuters reported that GM’s Korean unit could file for bankruptcy by Apr. 20 if the union there doesn’t agree to a reduction in labor costs.

In a statement to Bloomberg on Thursday, General Motors called the workers’ destruction a “violent incident” that caused “significant damage to company property.” No one was reported injured, but GM has promised to take legal action against those who trashed the office.