ISLAMABAD - At least 40 people were killed and over 300 others injured in a 7.9-magnitude earthquake that hit Pakistan on Tuesday afternoon, an official with National Disaster Management Authority (NDMA) told Xinhua on Wednesday.

Irshad Bhatti, spokesman of NDMA, said that all the causalities took place in Mashkel area of Washuk district in the country's southwestern province of Balochistan.

"The rescue teams have confirmed that 40 people have been killed and over 300 others injured and it is possible that the number of causalities could further rise as many people are still buried under debris," said Bhatti.

People stand outside of their office buildings following an earthquake tremor in Karachi April 16, 2013. [Photo/Agencies]

Bhatti said that Military Operations Directorate of Pakistan Army is leading the rescue operation and it has already sent the 62 Wing of Frontier Corps Balochistan and army troops along with teams of doctors and paramedical staff to the earthquake hit areas of Mashkel.

Army teams also airlifted food items, tents and medicine to the quake-hit areas via helicopters.

Talking about the difficulties in the rescue operation, the NDMA spokesman said that the scattered population pockets in the hit areas were affecting the disaster estimates and rescue operations.

NDMA authorities had already sent a request to the Pakistan Space and Upper Atmosphere Research Commission (SUPARCO) to get the imagery of the affected area to speed up the rescue operations.

According to the Pakistan Meteorological Office, an earthquake measuring 7.9 magnitude on the Richter scale hit southern and southwestern parts of the country on Tuesday afternoon with its epicenter located at a depth of 76 km in Iran's mountainous area of Khash near Pakistan border.

Inter Services Public Relations (ISPR), Pakistani army's spokesman, told media that two helicopters were taking part in the operation and had already lifted several injured from the affected areas and shifted them to the hospitals in the Washuk, Khuzdar and Quetta districts of the province.

Local media reported that over 1,000 houses in the earthquake-hit areas which are home to over 35,000 people, were destroyed in the earthquake.