Indian rescuers were working to free some 40 construction workers who were trapped when a road tunnel they were building collapsed in northern India on Sunday.
The tunnel collapse occurred in the Himalayan state of Uttarakhand.
Durgesh Rathodi, a state disaster response official, told the French AFP news agency from the site that some 200 meters (218 yards) of the 4.5-kilometer tunnel have collapsed.
"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," Rathodi said.
What do we know about the rescue efforts?
Local media said some 160 emergency personnel were involved in the rescue operations.
Rathodi said that a message was sent to the workers through a tube that is pumping oxygen into the blocked portion of the tunnel, assuring them that "all efforts are being made for your safety."
"No response to the message has come from inside yet," he told AFP.
Uttarakhand Chief Minister Pushkar Singh Dhami prayed for the workers' safety in a message on social media.
The tunnel is part of a road project launched by Prime Minister Narendra Modi. The Char Dham Project is meant to improve connections to the country's popular Hindu shrines, as well as areas bordering China.
Infrastructure construction accidents are common in India.