Ambulance and Fire tenders rush to the spot following Samardung tunnel collapse, reportedly trapping 12 workers, in Namchi on Monday. (Photo: Sikkim Police/ANI Video Grab)Over 20 were feared trapped inside an under-construction tunnel in Sikkim’s Namchi district on Monday after a landslide blocked its entrance and triggered a gas leak, news agency PTI reported.According to the district administration, though the exact number of workers trapped in the Samardung tunnel could not be ascertained, it is likely to be around 27.The presence of gas inside the tunnel continued to hinder the rescue operation, with several personnel feeling dizzy and falling unconscious while trying to reach the trapped workers, the officials said.According to them, the gas was probably emanating from the underground strata or rock formations, which are now disturbed by the landslide.District Collector Anupa Tamling said they got a distress call around 3.40 pm, following which rescue teams swung into action. Ambulances were on standby, while rescuers equipped with gas masks and other protective gear continued their efforts to reach the trapped workers.“It is estimated that 21 workers of contractor Patel Engineering and six of NHPC are stuck in the tunnel. Rescue operations are being carried out by teams of the National Disaster Response Force (NDRF), SDRF, district police and the Fire and Emergency Services. A specialised rescue team from neighbouring West Bengal has also joined the operation with gas-protective equipment for rescuers,” PTI quoted Tamling as saying. “The rescue operation is becoming increasingly difficult due to methane gas exposure, the narrow tunnel and poor visibility,” she added.The priority now is to rescue the workers trapped inside the tunnel, and a detailed probe into the incident will follow, Tamling assured.Story continues below this adPatel Engineering was constructing the tunnel as part of NHPC’s ADIT for the Teesta Stage VI Hydroelectric Power Project, they added.