(CNN) -- A powerful earthquake in southeastern Iran on Tuesday killed several people across the border in Pakistan, Pakistani officials said, but conflicting reports on casualties emerged from Iran.

Akbar Hussain Durrani, provincial home minister of Pakistan's Balochistan province, told CNN that six people had been killed by the quake and more than a dozen injured in the province's Washuk district.

The quake destroyed more than 50 shops in the district, Durrani said.

Earlier, Iran's state-run Press TV reported that at least 40 people had been killed in Iran, citing local reports.

But Iranian media, citing disaster officials, later said there had been no official reports of any deaths or serious damage in the quake, the strongest to hit the country in decades.

The U.S. Geological Survey said the earthquake was preliminarily measured at 7.8 magnitude.

"Thank God it doesn't appear that there is too much destruction," said a disaster official speaking live on a broadcast by IRIB from the city of Khosk.

The official described seeing five injured people and some cracked or collapsed walls, but no sign of major damage.

But the government was still gathering information and it was too early to tell the full extent of damage, the FARS news agency cited Mohammed Sarvar, deputy director of emergency affairs, as saying.

The Iranian Red Crescent has dispatched five assessment teams to the region, the aid group told CNN earlier Tuesday.

The Iranian Seismological Center said the earthquake, which it put at magnitude 7.5, had struck Iran's Sistan and Baluchestan province.

State of emergency

The epicenter of the quake, which struck about 3:15 p.m. local time, was about 50 miles (80 kilometers) north of the city of Saravan, the center said.

A state of emergency has been declared in the Saravan area, and rescue workers have been deployed from other provinces, the state-run IRNA news agency reported.

"Our teams have been deployed to the area for the first rapid assessment, but they have not reported back yet," Hassan Esfandiar, head of communications for the Iranian Red Crescent, told CNN.

The area is rural and sparsely populated, leading to hopes that casualty figures may not climb much higher.

Rescue workers are on their way to the scene, Iranian authorities said. No impact has been reported on any nuclear plants in the region.

Carrieann Bedwell, a USGS seismologist, said a 7.8-magnitude quake was "a large event for any area" and could be expected to cause damage in inhabited places.

Aftershocks can be expected for days or weeks after a quake of that magnitude, she said.

The USGS placed the epicenter 53 miles east-southeast of Khash, 103 miles northeast of Iranshahr and 123 miles southeast of Zahedan.

It initially said the quake had a depth of 15 kilometers (9.3 miles) but later revised that to 82 kilometers (51 miles.)

Shafiq Ahmed, an official with Pakistan's meteorological department, told CNN the tremor, which he put at magnitude 7.9, struck inside southern Iran, near the border with Pakistan.

Tremors were felt in southern Pakistan, including the city of Karachi, and across Balochistan province from Gwadar on the southern coast to Quetta and the border with Iran.

Gen. Saeed Aleem, chairman of Pakistan's National Disaster Management Authority, earlier told CNN there was no report of any casualties or damage to buildings in Pakistan, but information was still coming in.

'Children were crying'

Taghi Akhavan, an employee at Shaygan Hotel on the Iranian resort island of Kish, said he felt the quake around 3:30 p.m. local time.

He said several guests also reported feeling what they described as a mild tremor, but the hotel did not evacuate guests. He said he has not seen any damage.

Journalist Rabia Ali was among those to feel the quake in Karachi.

"I was at home. I was in my bed, and the bed started moving for a good 15 seconds," she said. "We realized it was an earthquake and we started evacuating. Everyone came out onto the street and started praying. The children were crying."

She said that she had not seen any damage in her neighborhood and that things have now calmed down.

The earthquake was felt as far away as Abu Dhabi, where buildings shook for 40 seconds or more, but it's not yet clear what damage has been caused across the region.

The latest earthquake comes on the heels of another last week in southern Iran, which left at least 37 people dead.

That quake, centered near the city of Kaki, was measured at magnitude 6.3. It did not damage the Bushehr nuclear plant, just over 60 miles away, according to Iranian state media.

CNN's Reza Sayah, Mitra Mobasherat, Brian Walker, Jo Shelley, Nasir Habib, Leone Lakhani, Saima Mohsin and Christine Theodorou contributed to this report.