The quake, followed by dozens of aftershocks, hit villages in the early morning hours in a mountainous area 50 km (30 miles) southwest of Shiraz, the main city in Fars province, state-run television said.
The strongest aftershock measured 5.4 on the Richter scale, it said.
The governor of Fars province told Tehran radio 20 villages and many roads, water installations, schools and rural clinics were heavily damaged.
"There has been heavy damage, partly due to the earthquake's power and partly because the buildings in the area were unstable," the official said.
He said virtually all the injured had been evacuated from the region.
The television showed footage of residents searching in the rubble of their homes as cows grazed outside a partly flattened stable.
Rescue teams from the military, police, and the Red Crescent have rushed tents, blankets and food to the area, the radio said.
- Reuters - Thomson Reuters Foundation
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