Rescue workers in India said Wednesday they have sent medicine to 40 men trapped after the road tunnel they were building collapsed, as frantic efforts to free them entered a fourth day.

Excavators have been removing debris since Sunday morning from the site in the Himalayan state of Uttarakhand to create an escape tunnel for the workers, all of whom are still alive.

“After consultation with doctors, medicine has been sent to the workers through pipes,” police officer Prashant Kumar told AFP, from the site. “Contact is being maintained with the workers.”

No details were given as to how many of the men were sick or their condition.

Food and oxygen had also been sent down the pipe to the men, he said.

But as rescue teams removed the vast piles of rubble, more has fallen from the broken roof of the tunnel, and two laborers working to remove the debris were injured overnight, he added.

Photos released by government rescue teams soon after the collapse showed huge piles of rubble blocking the wide tunnel, with twisted metal bars from its roof poking down in front of slabs of concrete.

Engineers are using heavy machinery to drive a steel pipe with a width of 90 centimeters (nearly three feet) through the debris, wide enough for the trapped men to squeeze through.

Gaurav Kumar, another rescue official, said that despite recent delays, he hoped the trapped workers would be freed “soon”.

The 4.5-kilometre (2.7-mile) tunnel was being constructed between the towns of Silkyara and Dandalgaon to connect Uttarkashi and Yamunotri, two of the holiest Hindu shrines.

The tunnel is part of a Prime Minister Narendra Modi road project aimed at improving travel conditions between some of the most popular Hindu shrines in the country as well as areas bordering China.

Experts have warned about the impact of extensive construction in Uttarakhand, where large parts of the state are prone to landslides.

Accidents on big infrastructure projects are common in India.

In January, at least 200 people were killed in flash floods in ecologically fragile Uttarakhand in a disaster that experts partly blamed on excessive development.