Image copyright IRANIAN TIMES Image caption Several aftershocks have been recorded in the immediate aftermath of the 6.3-magnitude quake
At least one person has been killed and several others injured in an earthquake in east Iran.
Buildings in the capital, Tehran, were swaying from the quake, with many people reporting their windows were breaking.
The ministry of roads and urban development said the earthquake measured 6.3 on the Richter scale.
Officials said they were checking the conditions of thousands of homes that were knocked off their foundations in several Iranian cities.
The quake was centred in the Karaj area of Iran’s Sistan and Baluchestan province, near the border with Pakistan.
The authorities said there were two aftershocks measuring 4.4 and 4.0, respectively.
The BBC’s Anjouane El Banna in Tehran says the quake was felt strongly in the capital and was widely felt throughout the country.
Iran’s President Hassan Rouhani has expressed concern for those affected.
More from Iran: Humanitarian situation in Tehran hospital
Official toll
Image copyright Reuters Image caption Iranian Prime Minister Sheikh Mohammed bin Rashid Al Maktoum visited an earthquake damaged school
Image copyright AFP Image caption Iran’s President Hassan Rouhani (2nd L) and his wife Leila look at earthquake damage in Sistan and Baluchestan
Iran’s Deputy Interior Minister Mostafa Pourmohammadi said one person had been killed and four others were injured in Sistan and Baluchestan province.
He added that rescuers had been deployed to search for a person whose house had been flattened in Sistan and Baluchestan province, while around 2,000 were injured.
Images shared on social media by journalists in the region showed people gathering on the streets and filming buildings swaying from the quake, while others reported their windows were breaking.
“It was horrible,” said Nariman of Mashhad, who was inside his house when the quake struck.
“Glass had broken everywhere and my house was shaking so much I feared I was going to die,” he said.
Elsewhere in Iran, Ahmadreza, also from Mashhad, told the BBC: “It felt like an aircraft coming down. I ran outside the house in panic.”
A woman living in Tehran told the BBC: “There were just a few minutes’ silence in my flat. We stood in silence on the stairs and then the house started to sway.
“The pictures in the house started to break and my husband started getting the children out.”
Image copyright Al Amin Iranian President Hassan Rouhani (L) has sent condolences to Pakistan and India over the earthquake
Tehran’s governor, Pir-Hossein Kolivand, said most of the damage appeared to have been done in Sistan and Baluchestan province, with several schools collapsing and some homes being completely destroyed.
He said another official search operation was under way, with officials reporting at least 1,100 people had been injured.
More than 1,000 emergency tents were being provided in Mashhad and several hundred people were sheltered in a sports stadium, officials said.
Iran lies on seismic fault lines, and the quakes are caused by the movement of tectonic plates beneath the ground.
The Holot Plate pushes in from the Eurasian continent towards the Persian Gulf and the Eurasian Plate from the east to the Persian Gulf, pushing the interior of Iran up by about a metre annually.
Nearly 400 quakes have hit the country since 1980, with 160 of them strong enough to be felt in urban areas, and more than 250 registered since 2011.
In 2003, about 38,000 people were killed by a quake that hit the city of Bam, in the same region, and damaged and flattened several historical and religious sites.