A man walks in a sandstorm at Guazhou toll station in Jiuquan, northwest China's Gansu Province, April 23, 2014. Parts of Gansu was hit by a sandstorm Wednesday afternoon, which reduced visibility to less than 50 meters, according to the provincial meteorological center. (Xinhua/Nie Jianjiang)

A northwestern Chinese city's strongest sandstorm in 10 years forced some schools to suspend operations on Wednesday.

The sandstorm started around 1:40 p.m. in Dunhuang, Gansu Province, reducing visibility to less than 20 meters, said an official with the city's weather forecast bureau.

As of 5:30 p.m., the sandstorm was still raging.

Schools sent parents circulars urging them not to send their children in on Wednesday afternoon.

The weather forecast station of Jiuquan City, which administrates Dunhuang, issued a sandstorm red alert, forecasting that visibility would be reduced to less than 50 meters throughout Jiuquan until Wednesday evening.