At least three labourers were trapped on Sunday when an under-construction tunnel near Bilaspur town in Himachal Pradesh collapsed, police said.
Fire brigade and police have launched a rescue operation to rescue them.
Official sources said the workers were digging the tunnel when a portion caved in due to landslides.
Machines have been deployed to pump oxygen into the tunnel, a police official told IANS over the phone.
The tunnel, which is part of the under-construction four-laning of the Chandigarh-Manali national highway, is located at Kandrour, between Bilaspur and Ghumarwin towns around 100 km from the state capital.
