The toddler boy, Yulen Garcia, was picnicking with his parents near the town ot Totaln on Sunday afternoon when he suddenly dropped down a 330-foot well.
He screamed out as he fell but hasn't been heard from since, RTE reports.
According to the AP , the tunnel was bored into last month during water prospection works and left unmarked.
Emergency crews, reportedly including more than 100 firefighters, have been working night and day since then to try and reach the boy.
But since the hole is only 10 inches wide, it's too small for an adult to climb down and pull Yulen out, so workers have been digging another tunnel to intersect with the main well, according to BBC News .
Crews were also considering digging a parallel hole, but there are fears that could destabilize the walls of the well.
On Monday, workers sent a camera down the well and found the candies and cup that the boy was carrying when he fell, about 229 feet down the shaft, NBC News reported . But they didn't see any sign of the boy himself before the camera became too wide for the passage.
Pilar Limon, a spokesman for the Emergencies Coordination Unit, told NBC News that they have been trying to widen the tunnel as well to get the camera down further.
According to BBC News, Yulen's parents, Vicky and Jose Garcia, lost their older son in another accident less than two years ago. Yulen's late older brother, Oliver, was three years old at the time of his death.
