They reportedly beat a management representative to death during their deadly protest.

About 2,000 workers dispatched by a trading company affiliated with North Korea’s Ministry of Defense occupied a medical manufacturing and seafood processing plant in the city of Helong, in northeast China’s Jilin province, on Jan. 11, the Yomiuri reported Saturday, citing North Korean sources as quoted by Radio Free Asia.

According to reports, several of the protesters were former female soldiers in their 20s.

They were reportedly angry about long-term wage arrears and took hostage the Chinese company’s management representatives and monitoring personnel from Pyongyang.

The North Korean authorities mobilized consuls and state security officers to try to restore order, but the workers prevented them from entering the factory, said Yomuiuri as quoted by Radio Free Asia, adding that the riot continued until the 14th of the same month, when the hostage management representative was beaten to death by the workers.

“It was the first large-scale protest by North Korean workers in China, and it brought to the surface the anti-authoritarianism of North Korean youth who refuse to accept slavery,” reads the Yomiuri report in part.

A North Korean source told the Japanese paper that those who led the riots will be sent to a political prison camp and punished severely.