The Fars news agency reported that scores of injuries were also caused by the powerful shaking, which also caused many homes and other buildings to collapse around the epicenter.
Panicked residents were reported to be huddling in the streets of Zahan, which lies near the capital of South Khorasan province, Birjand.
Some victims and survivors remained trapped in the rubble for hours after the quake struck at 8:39 p.m. local time.
One of the villages that appeared to have sustained the worst damage was Sharaj, where five people were killed, district governor Farhad Falahati told reporters.
The U.S. Geological Survey said the epicenter was at the relatively shallow depth of 18,000 feet, which contributed to the strength of the shaking at the surface.
More than a dozen aftershocks were said to have kept nerves on edge for the rest of Wednesday night.