Local television station K6 said that several of the attackers were shot by police and that victims were being transported to local hospitals.
The state-run Yunnan News said that the men were wearing uniforms when they stormed the railway station and that gunshots were heard after police responded.
Photos circulating online showed scattered luggage and bodies lying on the floor in blood.
The motive behind the attack was not immediately clear, but China has seen a number of mass stabbings and other attacks carried out by people bearing grudges against society.
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