At least 36 workers were reportedly trapped after a portion of a tunnel under construction between Silkyara and Dandalgaon on the Brahmakhal-Yamunotri national highway in Uttarkashi district in Uttarakhand collapsed in the early hours of Sunday, trapping around.

Police said the incident took place around 4am when a 150-metre-long portion of the four-and-a-half-kilometer-long tunnel collapsed.

As soon as information about the incident was received, Uttarkashi Superintendent of Police Arpan Yaduvanshi immediately reached the spot and launched a relief and rescue operation, news agency PTI reported.

National Disaster Response Force, State Disaster Response Force, fire brigade and employees of the National Highways and Infrastructure Development Corporation Limited (NHIDCL), the organisation that is constructing the tunnel, are at the spot as well, they said.

With the construction of this all-weather tunnel under the Char Dham Road Project, the journey from Uttarkashi to Yamunotri Dham will be reduced by 26 kilometres.

This is a developing story. Please check back for updates.