Guwahati/IBNS: The massive avalanche in Sikkim's Nathu La mountain pass on Tuesday left seven people killed, including a child and a woman, as many others are feared trapped under the snow.

"Massive avalanche hits tourists between Mile 13 & 17 on #Gangtok-Natu La Road. Troops of #TrishaktiCorps assisted by #BRO, SDRF & Police launch rescue mission. 27 personnel rescued so far out of which 7 succumbed to tragic incident. Rescue mission continues," the Indian Army said in a tweet.

Approximately 5-6 vehicles carrying 20-30 tourists on way to Nathu La are feared to have been stuck under the snow, the Army said.

Rescue operations are currently on with the Border Road Organization, police and the Army.

"About 350 others stranded have been rescued after clearing snow from the road," said Lt Col Mahendra Rawat.

The avalanche hit the region when several tourists were present near the snow-covered hillside of Jawaharlal Nehru Marg which connects Gangtok to the tourism spots of Tsomgo Lake and the Nathula border.

The calamity took place 15-17 Mile of Jawaharlal Nehru Marg at around 12.15 pm, about 25 km away from Gangtok.

Expressing distress, Prime Minister Narendra Modi assured that "all possible assistance is being provided to those affected".

"Distressed by the avalanche in Sikkim. Condolences to those who have lost their loved ones. I hope the injured recover soon. Rescue ops are underway and all possible assistance is being provided to those affected," the PM tweeted.

Nathu La Pass, at a height of 4,310 metres (14,140 feet) above sea level, is situated on the border with China and is a major tourist destination.

Videos from the site showed the magnitude of the tragedy as dozens of people including locals could be seen involved in rescue operations and trying to dig out those who are trapped.