The Construction Development Corporation Limited (CDCL) has confirmed that the accident at the tunnel construction of Nyera Amchu Hydropower Project in Martshala Gewog in Samdrup Jonkghar was caused by a gas explosion.
Four men lost their lives and another seriously injured in the accident that took place Friday morning.
CDCL officials said some gases were formed inside the tunnel, which is under construction. This triggered the explosion and release of harmful gases.
They said the explosion was not due to an undetonated explosive as reported earlier. Officials added explosives going off do not cause burn injuries like one of the victims has suffered.
Officials at the site also confirmed that the tunnel had not collapsed as reported earlier.
The four dead and the injured worker had gone to the tunnel to the clear the debris from a blasting carried out the day before when the tragedy struck.
CDCL is executing the tunnel construction works.
