A heavy, German-made drilling machine has been deployed to dig a parallel shaft to reach a 3-year-old boy stuck in an abandoned borewell at a depth of 88 feet for the last 77 hours, but rescue efforts were hampered by rocky soil and rain, officials said Monday.

Two Fire and Rescue Services personnel have been lowered into the freshly drilled shaft, using a ladder and with all necessary support like oxygen, for initial assessment of the condition inside, they said.

“We don’t know the condition of the child right now,” an official said.

As operations stretched into the fourth day, the sleepy village of Nadukattupatti, about 40 km from here, was teeming with people from neighbouring villages to witness the elaborate rescue efforts for the boy who fell into the disused farm borewell while playing near his house at 5.30 pm on Friday.

Officials on the site indicated that approximately 50 feet of parallel shaft has been dug up and after reaching further “right depth,” horizontal tunneling of about six feet is on the cards to reach the trapped child.

With authorities stepping up operations to pull out the boy, Prime Minister Narendra Modi on Monday said he spoke to Chief Minister K Palaniswami about the rescue efforts.

“My prayers are with the young and brave Sujith Wilson. Spoke to CM @EPSTamilNadu regarding the rescue efforts underway to save Sujith. Every effort is being made to ensure that he is safe,” the prime minister wrote on Twitter.

Rescuers have been digging the shaft since Sunday to reach an appropriate depth to get to the boy, and a heavy Larsen and Tubro drilling machine of German make, equipped with tungsten carbide tipped teeth, was deployed to expedite the efforts, said Commissioner of Revenue Administration J Radhakrishnan.

The abandoned borewell’s diameter is very narrow and the boy is trapped in rocky soil, he told reporters.

Initially, efforts were made to rescue the boy by using “clamping,” technology involving tailor-made equipment, but that failed, he said.

Geologists who were consulted pointed out that the soil comprised hard rock of quartz and feldspar, he said.

Monitoring through cameras indicates that the child is trapped at a depth of about 88 feet and some soil has fallen on him, the senior official said. But it is not clear what his condition is or whether he is conscious.

The child is in a “stabilised location,” and this point of space has been air-locked to prevent the boy from sliding down further.

“All technical efforts are in place to try and prevent the soil from getting loosened. The rescue operations will not be called off at any cost. There will be no let-up in the efforts. At the same time we don’t want to give any false hope to the parents of the child,” he said and added that they were being counselled.

Prayer meetings were held across Tamil Nadu for the safe rescue of the child and in several townspeople took out silent marches.

Chief Minister K Palaniswami said heavy-duty drilling machines and equipment have been deployed and experts from NLC, ONGC, L & T and NIT Tiruchirapalli are at the site.

“Further assistance would be sought depending on the status of the rescue efforts,” he said on his twitter handle.

Palaniswami said he briefed the Prime Minister on the rescue efforts.

“Three ministers have been deputed along with Fire and Rescue services, NDRF and SDRF,” he said.

National and State Disaster Response Force besides Fire and Rescue Services personnel are on stand by.

Following occasional mild showers, the location has been covered with tarpaulin sheets.