Six poachers have turned themselves in after allegedly killing a wildlife ranger in the northwestern province of Qinghai 17 years ago, local authorities said Monday.

The six surrendered after the public security bureau in the autonomous prefecture of Yushu expanded its hunt for the wanted men in September, said Li Yongqian, a police officer with the criminal police squad.

Sonam Dargye, a government official with Zhidoi county responsible for organizing anti-poaching work and who patrolled the Hoh Xil region frequently in person, was shot dead in January 1994, allegedly after 16 men poaching Tibetan antelope turned their guns on him, said Li.

One of the poachers was killed at the scene, and three others received sentences later from the death penalty to jail terms. Apart from the six who surrendered, five were still on the run, while one had died subsequently, said Li.

In 1997, the Hoh Xil National Nature Reserve was established to provide better protection for wildlife.

Sonam Dargye and the natural reserve became known following the release of the award-winning feature film in 2003, "Mountain Patrol" by Chinese director Lu Chuan. It tells the true story of a journalist who joined a Tibetan volunteer patrol chasing poachers trading antelope skins in Hoh Xil, which is spelled Kekexili in Mandarin.