These extraordinary images show how the power of an unprecedented dust storm swallowed Tehran, plunging Iran's capital into darkness and killing at least four people.
Many of the images of the storm's dark swell in the night sky were captured by horrified Iranians on their smartphones and thousands of them were posted to social media.
Around 30 people were injured in the swirling mass of sand from record winds that tore down trees and damaged buildings, according to AP. Iran's state IRNA news agency said winds hit 80mph (130kph).
The devastation caused a 20-vehicle pile-up on the motorway south of the capital. International flights are unable to get through to the city's airport and airplanes were diverted to central Iran, Al Jazeera said.
Those with heart or breathing problems have been told to stay indoors by the authorities.