Dehradun/IBNS: Several workers are feared trapped inside a tunnel in Uttarakhand after a part of the under-construction structure collapsed on Sunday. 

Rescue operations are on and attempts are being made to open the tunnel for rescuing the trapped workers.

The tunnel is meant to connect Silkyara to Dandalgaon in Uttarakhand's Uttarkashi.

It is being built under the Char Dham Road Project and aims to reduce the journey from Uttarkashi to Yamunotri Dham by 26 kilometres.

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

As information about the incident was received, the district administration sounded an alert and Uttarkashi Superintendent of Police Arpan Yaduvanshi reached the spot.

The rescue operations are being conducted by the State Disaster Relief Force (SDRF) and the police.

According to reports, 40 workers are feared trapped. Authorities said that nearly 200 metres of the slab will have to be cleared to open the tunnel.

A narrow opening has been made to insert an oxygen pipe in the tunnel and help the trapped labourers.

No casualties have been reported so far.