Many villages are hard to reach by road, hindering rescue efforts. Hospitals in Tabriz, Ardabil, and other cities nearby took in many of the injured, residents and Iranian media said, and there were long queues of survivors waiting to be treated.
"I wanted to go there last night to help but heard there was bad traffic and that it wasn't safe enough," Ahmad said. "People in those villages need help."
Aidin, a Tabriz resident, said he went to give blood at a local hospital on Saturday and saw staff struggling to cope with the influx of patients. Most patients had been taken there by their families, he said, indicating a shortage of ambulances.
Ahar's 120-bed hospital was full, said Arash, a college student and resident of the town. There were traffic jams on the narrow road between Ahar and Tabriz as victims tried to reach hospitals, he said by telephone.
"People are scared and won't go back into their houses because they fear the buildings aren't safe."
The US Geological Survey measured Saturday's first quake at 6.4 magnitude and said it struck 60 km (37 miles) northeast of the city of Tabriz, a trading hub far from Iran's oil-producing areas and known nuclear facilities.
The second, measuring 6.3, struck 11 minutes later near Varzaghan, 49 km (30 miles) northeast of Tabriz.
More than 1,000 villages in the area were affected by the earthquakes, Ahmad Reza Shaji'i, a Red Crescent official, told the Iranian Students' News Agency (ISNA). About 130 villages suffered more than 70 percent damage, and 20 villages were completely destroyed, he said.