A powerful earthquake hit Iran along its border with Pakistan early Tuesday. There have been reports of deaths in both countries, although accounts of the toll have varied widely. The area is sparsely populated, and rescue crews were still trying to reach the hardest hit areas through the day. Here's what has been reported so far:

The earliest reports were the most alarming
The quake hit at about 3:15 p.m. local time, and according to the U.S. Geological Survey it was a magnitude 7.8. Their counterparts in Iran said the magnitude was 7.5, while the Pakistanis estimated the magnitude at 7.9. USGS seismologist Carrieann Bedwell said such a powerful quake is "a large event for any area" and could be expected to damage population centers. Shortly after the quake, an Iranian official told Reuters: "It was the biggest earthquake in Iran in 40 years and we are expecting hundreds of dead." The last quake that powerful to hit Iran killed 15,000 people in 1978. Information on Tuesday's disaster trickled out slowly, as communications to the region were cut. The Iranian Red Crescent sent 20 search-and-rescue teams and three helicopters to aid the victims.

Iran's fears haven't been confirmed
As rescuers and locals reported back, the human toll, at least, appeared to be lower than feared. Iranian state media initially reported 40 deaths, but hours later said none had been confirmed. Experts gave two main reasons why there wasn't a heavier toll. First, while the Iranian province where it struck — Sistan Baluchistan — is the largest in the country, it's actually sparsely populated. Many of the inhabitants in the villages scattered around the epicenter live in tents, or mud huts. "The epicenter of the quake was located in the desert, and population centers do not surround it," said Morteza Akbarpour, an Iranian crisis center official. "There were no fatalities in the towns around the epicenter." The second reason for the light damage appeared to be that the quake hit deeper underground than first thought. The USGS initially reported the depth at nine miles, and later revised the estimate to 51 miles.

Pakistan may have suffered the worst
Deaths have been confirmed on Pakistan's side of the border, where, according to local leaders, at least five people died in the town of Mashkel. Agence France Presse says a total of 34 people were killed in Pakistan. The earthquake was strong enough to be felt across the region, from New Delhi, India, to Dubai. Michael Stephens, a researcher at RUSI Qatar, told BBC News from his office in Doha: "I definitely felt the walls shaking. It lasted for about 25 seconds." Authorities in Karachi (Pakistan), Delhi, and in Gulf states evacuated office buildings that shook during the event, although no damage was reported in cities far from the epicenter.

Iran's nuclear plant dodged another bullet
Tuesday's quake was the second to strike Iran recently — a 6.3 magnitude quake struck near the Persian Gulf coast last week. That disaster left 37 people dead and it hit just 60 miles from the town of Bushehr, which is home to Iran's nuclear power plant. The event conjured up fears of a nuclear nightmare like the one that occurred when Japan's earthquake and tsunami triggered a meltdown at the Fukushima nuclear plant. Those fears weren't realized, however, as the reactor was apparently not damaged. But both Iran and Pakistan have many other nuclear facilities, from research labs to uranium mines. "Given the magnitude of the quake... it's not yet clear if [all of] the regime's nuclear facilities escaped the damage," said John Hudson at Foreign Policy.