TEHRAN, Iran (CNN) -- The death toll from two strong earthquakes that struck northwest Iran was likely to climb Sunday as crews scoured communities reduced to rubble by temblors and aftershocks.
A third earthquake struck early Sunday morning in the same region, according to the U.S. Geological Survey. There were no immediate reports of damage or casualties.
At least 250 people were killed and 2,000 injured in Saturday's earthquakes, state-run Press TV said, quoting the Interior Ministry. The quakes struck near Tabriz, the country's fourth-largest city.
Other state news agencies put the toll at 180 dead.
The cities of Ahar and Varzagan are the hardest hit, with at least 220 people killed and an additional 1,500 wounded, Khalil Saei, the provincial director of crisis management, told the Islamic Republic News Agency.
Initial reports said some buildings in Tabriz suffered structural damage and power lines were down. Telephone lines were down in Ahar, the quake's epicenter. Officials are assessing the extent of the damage.
The first earthquake, a magnitude 6.4, hit Saturday at 4:53 p.m. local time, 37 miles northeast of Tabriz, according to the U.S. Geological Survey, which measured 11 aftershocks. Just 11 minutes later, a second quake, measuring 6.3, struck 30 miles northeast of Tabriz.
On Sunday morning, at 7:55 a.m. local time, a magnitude-4.0 earthquake struck just outside of Ahar, the USGS said.
Authorities reported dozens of aftershocks in the region following the quakes and asked residents to spend the night outdoors as a safety precaution.
The quakes affected Tabriz, the capital of East Azarbaijan province, and nearby cities. They razed four villages and 60 others sustained heavy damage, Fars said.
Many people are in dire need of drinking water, bread and shelter, Fars said.
Iran sits on major fault lines -- the collision of the Arabia and Eurasia plates -- and has been prone to devastating earthquakes.
Nine years ago, 30,000 people died in an earthquake in Bam in southeastern Kerman province. In 1990, about 50,000 were killed in a quake that hit near the Caspian Sea.
CNN's Shirzad Bozorgmehr and Ben Brumfield contributed to this report.
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