At least five people have been killed and hundreds more injured in an earthquake in northwestern Iran, officials said say.
The 5.9 magnitude tremor struck in the early hours of Friday in East Azerbaijan province, Iran's Seismological Center said.
Most of the injuries were caused by crowd stampedes, state-run TV reports.
Iran sits on two major tectonic plates and is prone to frequent seismic activity.
In 2003, a 6.6 magnitude earthquake destroyed the historic city of Bam in the south-east of the country, killing 26,000 people.
More recently, in 201
- Iran-Iraq border earthquake is deadliest of 2017
What happened to the latest quake?
struck near the town of Tark, some 400km (250 miles) north-west of capital Tehran, at 02:17 local time (22:47 GMT).
As well as killing five people, the quake injured 312 – though only a dozen or more of them required treatment in hospital.
"Rescue teams and helicopters have been dispatched to the quake-hit areas and hospitals are on full alert to help injured people," Iran's emergency medical services chief, Pirhossein Kolivand, told state TV.
State-run IRINN TV said most of the injuries were due to overcrowding as people rushed out of their homes and into the streets in panic.
Up to 30 homes were destroyed near the epicenter, it added. More than 60 aftershocks have been reported.
Rescue workers are operating in 41 villages, but most of the damage was concentrated in the two villages of Varnakesh and Varzaghan, provincial governor Mohammad-Reza Pourmohammadi was quoted as saying.
Emergency services have been distributing survival kits, cooking equipment, blankets and tents, according to AFP news agency.
According to the US Geological Survey, the epicenter of the earthquake was at a depth of 10km, although Iran's Seismological Center said it was at a depth of 8km. Shallower earthquakes are more likely to cause greater damage.
Tremors were reportedly felt as far away as Tehran.