The death toll from a 7.1-magnitude earthquake in northwest China's Qinghai Province has risen to 617, rescuers said Thursday.

The latest statistics show that 313 people were missing and 9,110 injured, 970 severely, said a spokesman with the rescue headquarters in?the Tibetan Autonomous Prefecture of Yushu in southern Qinghai.

Almost 2,000 soldiers, police officers and fire-fighters were carrying out search and rescue operation in the Gyegu Town, the seat of the Yushu prefecture government, the spokesman said.

More rescuers were en route to the town that is close to the epicenter and home to 100,000 residents, he said.

The quake struck the Yushu County in the Yushu prefecture at 7:49 a.m. Wednesday with a depth of about 33 km. The epicenter was calculated to be 33.1 north and 96.7 east, the China Earthquake Networks Center reported.

A series of aftershocks have been reported so far, with the biggest being at 6.3 magnitude.

The epicenter is at the Rima Village in the Shanglaxiu Township, a pasturing and sparsely-populated area about 50 km west of Gyegu and about 800 km away from the provincial capital Xining.

Many people are still buried in the debris as more than 85 percent of houses in Gyegu, mostly made of mudbrick and wood, had collapsed.