Nepal's National Emergency Operations Centre have confirmed that at least 3,726 people have died after the country experienced a 7.8 magnitude earthquake and a subsequent 6.7 magnitude aftershock.
The tremors have caused extensive damage to buildings and infrastructure in the capital Kathmandu. Hundreds of people are understood to still be trapped under rubble, including that of the city's landmark Dharahara tower.
The quake struck 80km (50 miles) east of the central city of Pokhara but tremors were felt as far away as India's capital New Delhi, Pakistan and Bangladesh.
Residents in Kathmandu have been warned to stay outdoors, enduring a second night camping in freezing temperatures.
Rescue teams from countries including Britain are understood to be on their way to Nepal but the main airport in the capital, initially closed, is now struggling to cope.
Initial reports on the situation at Headquarters British Gurkhas Nepal came from its Commander, Colonel Sean Harris.
South of the river in the city all staff were quickly accounted for with only a few minor injuries among staff.
Many of those on the base, as well as those from British Gurkhas Pokhara and Dharan are now involved in the immediate search and rescue operation.
Having sustained damage to their own buildings in Kathmandu, UK staff from the Department for International Development have moved into the Gurkha HQ. The British School is also considering relocating for security and accommodation.
The British Embassy also survived the massive tremor intact. Most areas of the city remain without power and water.
The earthquake triggered a series of avalanches on Mount Everest causing substantial damage to the mountain's base camp.
1000 climbers are believed to be in the region with around 300 of those at Everest base camp. At least 18 people are reported to have died.
Captain Tim Bradshaw, from a British Army team currently attempting to climb the world's highest peak, told Sky News his tent "started to rock and move" as the earthquake hit.
"Then almost like thunder, huge boulders started to break around us from the side of the mountain and roll down towards the bottom, towards base camp," he said.
"Everyone here is fine ... but we are on the other side of the mountain away from the Nepal side, quite away from the epicentre."
Members of the Gurkhas Everest Expedition Team have all been accounted and sustained just one minor injury.
The fate of a number of climbers actually up the mountain is unknown, with approximately 100 thought to be trapped between Camp 1 and 2 with no passable route down.
The Foreign Office has advised that any British Nationals in need of consular assistance call +44 (0) 207 008 0000 or text NEPAL to +447860010026.