Two people died and 38 were injured when a 5.1 magnitude earthquake struck northern Iran in the early hours of Friday and people fled their homes in panic, state television reported.
There were at least 40 milder aftershocks, but no serious damage from the quake that struck after midnight on the border of the provinces of Tehran and Mazandaran, it added.
The shallow 4.6 magnitude quake hit at 00:48am (2018 GMT) near the city of Damavand, about 55 kilometres east of Tehran, the US Geological Survey (USGS) said.
An Iranian woman and her daughter sit outside their home in Tehran. AFP
It saw scores of residents of Tehran flee buildings for the safety of the capital's streets and parks, AFP journalists reported.
Many spent the rest of the night sleeping in their cars on the side of the road, apparently too fearful to return to their homes.
Some wore face masks, a sign of the times in a country already struggling to contain the Middle East's deadliest outbreak of the coronavirus pandemic.
Soon after the quake struck at 00:48 local time Friday (2018 GMT on Thursday), officials urged people who spent the night outdoors for fear of aftershocks to observe social distancing to limit spread of the new coronavirus.
Authorities also assured the public there was no shortage of petrol as people rushed to gas stations to fill up after the quake.
Among the dead were a 21-year-old woman in Tehran who suffered heart failure, and a 60-year-old man in the city of Damavand, east of the capital, killed by a head injury, officials said.
Tehran governor general Anoushirvan Mohseni-Bandpey told state TV that only four of the 38 injured were hospitalised.
The temblor struck as Iranians were either sleeping or resting after Iftar. "We were sitting down when the earthquake struck," said 45-year-old Tehran resident Ahmad.
"We felt it completely shaking (the building), and then we all went out of the house together to be outside and not to be in danger if an aftershock struck," his wife Maryam, who like him was wrapped in a blanket, said they escaped the apartment using the stairwell.
"We quickly took the children by their hands and got out," said the 37-year-old housewife.
Agencies