Two strong quakes that struck towns and villages in northwest Iran in quick succession on Saturday killed at least 50 people and injured hundreds, according to a preliminary toll by officials.
"According to the latest reports, about 40 to 50 people have been killed in the quakes today.... About 400 have also been injured," the head of Iran's emergency services, Gholamreza Masoumi, was quoted as saying by the ISNA news agency.
Masoumi said those hurt were being taken to hospitals in Tabriz and Ardebil, the two biggest nearby major cities, both of which escaped relatively unscathed by the temblors.
The quakes measured 6.2 and 6.0 on the moment magnitude scale, according to Tehran University's Seismological Centre.
The US Geological Survey, which monitors seismic activity worldwide, ranked them as more powerful than that, at 6.4 and 6.3, respectively.
"Sixty villages... have been heavily damaged and are in need of help," a lawmaker in the hard-hit town of Ahar, Abbas Fallah, told the Mehr news agency.
The coroner for Ahar, Mohammad Zargari, told the Fars news agency that in that area "so far 20 people have lost their lives... (but) it is estimated the number will reach 40."
The provincial chief coroner, Bahram Samadi-Rad, said another 30 dead were counted in Varazqan, another town that was badly shaken.
"So far 30 corpses from the quake-hit town of Varazqan have been given to the coroner's office," he said, according to Fars.
Allahverdi Dehqani, a lawmaker in Varazqan, confirmed that "most of the villages around Varazqan have been damaged."
Residents in the region panicked as their homes shook around them when the quakes hit, sending them fleeing into the streets for safety, according to reports.
Telephone communications were cut for hours, forcing rescue personnel to use radios and to send helicopters to some of the villages to assess the extent of the disaster.
Rescue operations were continuing into the night.
Tehran University's Seismological Centre said the first earthquake hit at 4:53 pm (1223 GMT) with an epicentre just 60 kilometres (40 miles) from Tabriz, close to the town of Ahar, and a depth of 10 kilometres.
The second -- a big aftershock -- rumbled through just 11 minutes later from nearly the same spot. A series of 17 smaller aftershocks rating 4.7 or below rapidly followed.
Iran sits astride several major fault lines and is prone to frequent earthquakes, some of which have been devastating.
The deadliest was a 6.6-magnitude quake which struck the southern city of Bam in December 2003, killing 31,000 people -- about a quarter of the population -- and destroying the city's ancient mud-built citadel.