“The students rushed to escape the school building in Taluqan city (capital  of Takhar), triggering a stampede,” Takhar education department chief Enayat  Naweed told AFP.

“Twelve students, all minors, were killed and 35 others were injured.” 

The quake struck 250 kilometres (160 miles) northeast of the capital Kabul, in the remote area of the Hindu Kush mountain range just shortly after 2pm Pakistan Standard Time.

It had a depth of 213.5 kilometres (132 miles), the US Geological Survey said.

The USGS initially measured the quake's intensity at 7.7 then revised it down to 7.6 and later to 7.5.

At least one aftershock hit shortly afterwards, with the USGS putting its magnitude at 4.8.

In a statistical prediction on its website, the agency said there was a one-third chance of the number of fatalities climbing to between 100 and 1,000  people, with several million dollars’ worth of damage likely caused.

 The rescue effort was being complicated by the lack of communications, with  the region’s already-fragile infrastructure hit.

Gul Mohammad Bidar, deputy governor of Badakhshan in Afghanistan, told AFP  lines were down and it was difficult to reach stricken communities.

“The earthquake was very powerful -- buildings have been damaged (in  Faizabad) and there are possible casualties. We have sent a team around the  capital Faizabad to assess the scale of the destruction.”

Cellphone networks were down in the Kashmir region, where panicked  residents also evacuated buildings and children were seen huddling together  outside their school in the main city of Srinagar.

“Some bridges and buildings got damaged. There are no reports of loss of  life so far. Cellphone networks are down, we are using our wireless network to  gather information,” police inspector general in Kashmir, Javid Gillani, told  AFP.

Many buildings were badly damaged during massive floods in Kashmir a year  ago, heightening the danger of collapse during the quake.

Pakistan mobilised its troops and all military hospitals have been put on  high alert, army spokesman Lieutenant General Asim Bajwa said, adding that  specialised earthquake rescue machinery and army helicopters were being readied  for use.

The Pakistan Air Force said it was offering full support to the National  Disaster Management Authority.

Arbab Muhammad Asim, district mayor for Pakistan’s northwestern city of  Peshawar, said more than 100 people had been injured there alone.

“Many houses and buildings have collapsed in the city,” he said.

Dr Muhammad Sadiq, the head of emergency services at a government hospital  in Peshawar, confirmed the number of injuries.

“Many more injured are still coming to hospital. Many are still under rubble,” Sadiq told AFP.

Buildings shook violently in Kabul and tremors were felt across northwestern Pakistan and its central Punjab province.

In the Pakistani capital, walls swayed back and forth and people poured out of office buildings in a panic, reciting verses from the Quran.

Zahid Rafiq, an official with the meteorological department, said the quake was felt across the country. In Islamabad, buildings shook and people poured into the streets in a panic, with many reciting verses from the Quran.

“I was praying when the massive earthquake rattled my home. I came out in a panic,” said Munir Anwar, a resident of Liaquat Pur in the eastern Punjab province.

Officials in Pakistan said communications had been cut off to remote areas, making it impossible to get reports on conditions in those areas.

They said ambulances have been dispatched from Abbottabad to some of the mountainous areas worst affected in Pakistan’s last major earthquake, in 2005.

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As buildings shook throughout north India, hundreds poured onto the streets and car parks  from office blocks, hospitals and and homes.

New Delhi’s metro ground to a halt during the tremor although the airport  continued operating, no damage was immediately reported there.

The earthquake struck almost exactly six months after Nepal suffered its worst quake on record, on April 24. Including the toll from a major aftershock in May, 9,000 people lost their lives and damaging or destroying 900,000 homes.

The mountainous region is a seismically active region, with earthquakes the result of the Indian subcontinent driving into and under the Eurasian landmass. Such tectonic shifts can cause enormous and destructive releases of energy.

The epicentre is just a few hundred kilometres from the site of a 7.6  magnitude quake that struck in October 2005, killing more than 75,000 people  and displacing some 3.5 million more, although that quake was much shallower.

With reporting from Agence France-Presse, Associated Press and Reuters