A Chinese court sentenced three people to death and one to life in prison on Friday for an attack at a train station that triggered a sweeping crackdown on what Beijing calls militant violence.

The government said knife-wielding militants from the western region of Xinjiang launched a premeditated attack in March at the Kunming station in the southwestern province of Yunnan, in which 31 people were killed and 141 injured. Police shot dead four of the attackers.

China's leaders have vowed to strike hard at religious militants and separatist groups, which they blame for a series of violent attacks in Xinjiang, the traditional home of the Muslim Uighur ethnic minority.