Security is on high alert at this train station in southwestern China.

Armed riot police stood guard as people streamed into the Kunming station in Yunnan province. It's been just hours after a chilling mass knife attack left at least 29 people dead and more than 130 injured.

Witnesses say a group of knife wielding attackers burst into the station and began stabbing people at random.

(SOUNDBTE) (Mandarin) PARKING ATTENDANT MR. CHEN STANDING SAYING:

"Two women said to me: 'There's fighting outside, they're killing people'. I said: 'Don't talk nonsense, it's very safe here'. But that people really were being killed. So I walked out and I saw a person with a knife this big. I thought it was just one person, so I planned to shout for a couple of people to try and apprehend them, but then I saw five or six of them. They all had knives and they were stabbing people madly over by the first and second ticket offices."

(SOUNDBITE) (Mandarin) SUPERMARKET WORKER REN