China's north-west region is on high alert for sandstorms after one blanketed Aksai Kazakh Autonomous County in Gansu Province.
The wall of sand was whipped up by strong winds, reducing visibility to just 10 metres in 10 minutes.
The authorities managed to issue a warning to close doors and windows and wear masks outdoors.
China has a four-tier colour-coded system for severe weather, with red being the most serious, followed by orange, yellow and blue.
The local meteorological station issued a yellow sandstorm warning with more storms expected in the next 12 hours.
Environmentalists say logging and over-grazing has led to erosion, increasing the frequency and severity of such storms.