URUMQI, June 16  -- Thirteen people were executed on Monday for terrorist attacks and violent crimes in northwest China's Xinjiang Uygur Autonomous Region.

They were involved in seven cases and convicted of organizing, leading and participating in terrorist groups; murder; arson; theft; and illegal manufacture, storage and transportation of explosives, according to local courts in prefectures of Aksu, Turpan and Hotan.

All death penalties have been approved by the Supreme People's Court, as required in China.

The 13 planned attacks and killed police officers, government officials and civilians. They took innocent lives, caused huge property losses, and seriously endangered public security, according to local courts.

In one case, three defendants -- Ehmetniyaz Sidiq, Abdulla Srepli and Gulam Eli-- were convicted of organizing and leading terrorist attacks on a police station, hotel, government office building and other venues, killing 24 police officers and civilians and injuring 23 others at Lukqun Township in Shanshan County of Turpan Prefecture on June 26 last year.

In another case, Abdujelil Metnasir joined a terrorist group in February 2012 under the influence of extremism, participated in illegal religious activities many times and led physical training for terrorists. In May 2012, he and other members of the group killed two members who wanted to quit, and planned the assassination of government officials. In June 2012, he provided the bombs that killed one child and injured 17 others at an illegal preaching venue.

"The execution of criminals involved in terrorist attacks and violent crimes answers the calls of all ethnic groups, deters criminal activities, and demonstrates the resolve of the Communist Party of China and the government in cracking down on terrorism," said a spokesman of Xinjiang regional higher people's court.

He said the local judicial organs will continue to perform their functions; severely punish terrorists and criminals using legal weapons; defend the dignity of the law; and safeguard fairness, justice, social harmony and stability.

Also on Monday, three other people were sentenced to death by the Urumqi Intermediate People's Court over a terror attack near Beijing's Tian'anmen Square in October 2013.

A year-long crackdown on terrorism was launched in China with Xinjiang as the major battleground after a terrorist attack on May 22 in an open market in the regional capital Urumqi. The attack, the deadliest in recent years in the region, killed 39 innocent people and injured 94 others.