A massive earthquake of magnitude 7.8 struck the Iran-Pakistan border region at 10:44 GMT on Tuesday at a depth of 15.2 km (9.4 miles), according to the US Geological Survey.
The earthquake struck in the province of Sistan Baluchistan close to the cities of Khash and Saravan. The population of both the cities are 180,000 and 250,000 respectively.
Hundreds are feared dead, but the an Iranian lawmaker said that the number of deaths was "not high", reported Reuters.
"From what we have heard from people in the stricken areas, we have learned that the number of deaths is not high," Hamid Reza Pashang was quoted as saying by the news agency.
ISNA news agency also quoted an Iranian crisis center official saying that there were no deaths reported so far.
In Pakistan, at least 21 people were killed according to hospital and local government officials.
Rescue teams have been sent to the affected areas. Five evaluation teams have also been dispatched to assess the damage caused by the earthquake.
The strong earthquake is the worst one to strike Iran in 40 years. It has occured just a week after a strong quake ripped through Iran's Gulf port city of Bushehr, where atleast 30 people were killed and 800 injured.
Tremors Felt in India
Tremors were felt in the capital city of New Delhi, NCR, Chandigarh, Jaipur and Ahmedabad and parts of northern India, as well as in the Middle East and the Gulf region.
Latest reports said that tall buidings in the capital city of Delhi swayed for 10 seconds. In some places, the quake triggered panic causing frightened people to run into the streets.
According to India's disaster management authority, the tremors were felt as a result of the earthquake in Iran.
As of now, there has been no reports of damage or loss of life in the captial city.
In the Gulf, officials ordered evacuations. People were rushed out from shaking buildings in Qatar and Dubai, reported Reuters.
"It seems as if the buildings will fall any minute," an unidentified man in Karachi told GEO News, a private television news network.