A court in China executed three men on Tuesday for leading an attack on a train station that left 31 dead.

State news agency Xinhua reported that the trio had previously been sentenced to death for murder, along with organizing and leading a "terrorist" organization.

On March 1, 2014, a group armed with knives randomly attacked people at the station in Kunming, the capital of southwest China's Yunnan Province.

Along with the 31 people killed, another 141 were injured.

Four of the attackers were shot dead by police, and a pregnant female suspect was wounded, captured, and has since been sentenced to life in prison.

The Kunming Intermediate People's Court said that Iskandar Ehet, Turgun Tohtunyaz and Hasayn Muhammad - all from the from the far western region of Xinjiang - were executed on Tuesday upon approval by the Supreme People's Court.

Xinjiang, home to the Muslim Uighur minority group, has been plagued by unrest in recent years. Some Uighurs have chafed under Chinese restrictions on their culture and religion.

Rights groups have expressed concern about executions and mass-sentencings carried out regularly since an upswing in violence blamed on Xinjiang militants took place last year.