An unexpected sandstorm, the second one this year, attacked this capital of northwest China's Gansu Province Wednesday afternoon.
The sandstorm was caused by hot convection in the area, as the temperature had climbed quickly since the last sandstorm, which occurred March 28, according to Yang Jiancai, chief forecaster of the provincial meteorological center.
Heavy sandstorms also affected areas around the provincial capital, while some areas witnessed rain, snow or hail, Yang said.
Lanzhou is one of the major victims of sandstorms among all Chinese cities. So far, the city has suffered deposits of 300,000 tons of sand and dust particles this year.
The sandstorms have also caused a growing number of local people to suffer from respiratory problems, according to local hospitals.