At least five people have been killed and more than 300 injured in an earthquake which struck north-west Iran in the early hours of Friday morning, an emergency official said.
Pirhossein Koulivand told state TV about the deaths and injuries early on Friday morning.
The earthquake struck about 120 kilometres south-east of the city of Tabriz, in East Azerbaijan province, in the early hours of the morning, the Iranian Seismological Center said.
The earthquake measured 5.9 on the Richter scale, prompting the US Geological Survey to issue an alert warning that "significant casualties are likely and the disaster is potentially widespread".
State TV reported the earthquake destroyed 30 homes at its epicentre. The rural region in the Alborz Mountains was hit by more than 40 aftershocks.
An orange alert has been issued for fatalities and the USGS is predicting that between 100 and 1,000 people could have been killed by the quake.
The USGS said the tremor struck at 2.17am local time.
Iran's IRNA news agency said the tremor was relatively strong and caused many people to run out of their homes in panic in the middle of the night and state TV said the quake was felt in several towns and cities.
The European-Mediterranean Seismological Centre (EMSC) said the quake was felt by some 20 million people.
The quake had a shallow depth of 10km, which would have amplified the shaking.
Iran sits where two major tectonic plates meet and sees frequent seismic activity.
The country has suffered a number of major disasters in recent decades, including at the ancient city of Bam, which was decimated by a catastrophic earthquake in 2003 that killed at least 31,000 people.
In 1990, a 7.4-magnitude quake in northern Iran killed 40,000 people, injured 300,000 and left half a million homeless, reducing dozens of towns and nearly 2,000 villages to rubble.
Iran has experienced at least two other significant quakes in recent years – one in 2005 that killed more than 600 people and another in 2012 that left some 300 dead.
