A knife-wielding man who killed two security guards and injured another at a university in southwest China's Guizhou province earlier this week has a history of mental illness, local police said.

A 30-year-old man surnamed Xu tried to enter Guizhou Normal University at 12:38 p.m. Monday. Security guards attempted to stop him from entering after noticing that he was brandishing a knife, said police from the provincial capital of Guiyang.

Three of the guards were injured while fighting with Xu. Two guards died from their injuries at a local hospital, the police said.

Xu was apprehended by the police after injuring the guards.

Xu was found to have had an eight-year history of mental illness. He received treatment at the Guizhou Province No. 2 People's Hospital from November to December last year, police said.

Xu was required to take medication to control his mental stability but refused to take the medication regularly, the hospital's doctors said.

Xu was not medicated on the day of the attack, the doctors said.

A further investigation into the case is under way.