Tragedy struck a group of 15 tourists from Kerala in Nepal when eight of them, including four minors, died after they fell unconscious probably due to a gas leak from a heater in their room at a mountainous resort, police said, amidst cold wave in the Himalayan region.

The Indian nationals were airlifted to HAMS hospital in Kathmandu where they were pronounced dead on arrival, superintendent of police Sushil Singh Rathaur said.

Makwanpur police said the victims might have fallen unconscious due to asphyxiation.

'All eight were airlifted and brought to hospital in Kathmandu. A doctor from the Indian mission was also immediately sent to the hospital concerned to check on welfare of patients and to provide necessary assistance,' a source at the Indian Embassy in Kathmandu told PTI.

'We have now been informed that all eight patients did not survive,' the source added.

The victims were identified as Praveen Krishnan Nair, Saranya Sasi, Sreebhadra Praveen, Aarcha Praveen, Abhinav Saranya Nair, Ranjith Kumar Adatholath Punathil, Indu Lakshmi Peethambaran Ragalatha and Vyshnav Ranjith.

The deceased - two couples and four children - were part of a group of 15 people travelling from Kerala to Pokhara, a popular mountainous tourist destination.

They were on their way back home and stayed at Everest Panorama Resort in Daman in Makawanpur district on Monday night.

According to the manager at the resort, the guests stayed in a room and turned on a gas heater to keep themselves warm.

Although they had booked a total of four rooms, eight of them stayed in a room and remaining others in another room, the manager said, adding that all the windows and the door of the room were bolted from inside.

'Deeply distressed by the tragic news of the passing away of eight Indian tourists in Nepal,' external affairs minister S. Jaishankar tweeted.

He said the Indian embassy officials are stationed at the hospital and are providing necessary assistance.

The Indian mission has assured all necessary assistance to the family members of the victims.

In Thiruvananthapuram, Kerala chief minister Pinarayi Vijayan condoled the death of Malayali tourists in Nepal.

On the directions of the chief minister, officials have taken steps to expedite procedures for the repatriation of the mortal remains of the victims, his office said.

Minister of state for external affairs V. Muraleedharan said that Indian Embassy officials were taking steps to bring the bodies back to India as early as possible.

Nepal witnesses cold wave condition between December and January. Daman is a famous hill station situated 70-km south of Kathmandu, where people visit for magnificent mountain view.