BEIJING (AP) _ Hundreds of thousands of mice have drowned themselves in northwest China in a mass suicide possibly triggered by overpopulation, the Xinhua News Agency said Wednesday.

Herdsmen began finding dead mice in May in the Altay Grassland and nearby parts of the Xinjiang Uygur Autonomous Region, the official news agency said.

The numbers grew quickly, and more than 300,000 dead mice were scooped up at one location, Xinhua said.

Scientists have not found any signs of disease in the rodents, and there are no reports of disease among other animals or people in the region, the report said.

Xinhhua said the mouse population had been growing for several years, and experts speculated that overpopulation had caused some to fall victim to a mysterious disease.

''Others wonder if this is a premonition of an unprecedented drastic earthquake,'' the report said.