Xinhua News Agency says police fatally shot four of the assailants, leaving 33 people dead and 130 others wounded.
A witness says the suspects, most of them dressed in black, stormed the Kunming train station in Yunnan province and started attacking people in the late evening. Xinhua says one was arrested.
The agency quotes the municipal government as saying that evidence found at the scene shows it was "a terrorist attack carried out by Xinjiang (shihn-jahng) separatist forces. Authorities consider it to be "an organized, premeditated violent terrorist attack."
The far western region of Xinjiang is home to a simmering rebellion against Chinese rule by separatists among parts of the Muslim Uighur population.