At least 40 construction workers were trapped Sunday after the road tunnel they were building collapsed in northern India, with rescuers scrambling to reach them beneath piles of debris.

"About 40 to 41 workers are trapped inside. Oxygen is being supplied through the debris, but more rubble is coming down as rescuers try to remove the obstruction," Durgesh Rathodi, a disaster response official in the Himalayan state, told AFP from the site.