Rescuers in southern Spain have began drilling in the hope of rescuing a two-year-old boy trapped in a deep well for six days.

The mission to save the child has triggered an outpouring of public support as rescuers struggle with the challenge of bringing heavy equipment up steep access roads and reaching the toddler safely.

“We are incredibly motivated to reach him as soon as possible. We’re not bothered by the hours, the tiredness or the lack of sleep,” Ángel Vidal, the lead engineer overseeing the rescue, said on Saturday.

“We are hopeful that we will reach him as soon as possible and bring him back to his parents,” he added.

However, on Sunday the effort slowed as diggers hit hard granite. Rescuers would complete the vertical shaft “at the end of the night” on Sunday if they are able to keep working at the same pace, engineer Angel Garcia Vidal who is overseeing the operations, told reporters late on Sunday.

“We continue to work intensely, nonstop, and we hope to reach our desired goal very soon,” he added.

The boy, Julen Roselló, fell into the borehole, which is just 25cm (10 inches) wide and 100m (yards) deep, as his family walked through a private estate in Totalan, Málaga.

Officials have been unable to find signs of life but say they are working on the basis that the child is still alive. Video footage shot by firefighters and released by Spanish broadcaster Canal Sur shows a blockage around 70 metres into the well which has prevented rescue services from sending food or water to the child.

Experts told Spanish media that there are slim chances that Julen could still be alive, explaining that cold weather slows a body’s metabolism, so it needs less energy and can survive with abnormally low breathing and blood flow.

“The cold has a double edge. On the one hand it’s negative, because it can cause multiple consequences,” Ivan Carabano, a paediatrician at Madrid’s Hospital 12 de Octubre, told the El Pais daily.

“But in this case we all hope for its better outcome: with it you gain time to survive because at lower temperatures the human metabolism slows and tissues are preserved.”

Trucks brought drilling equipment and giant pipes to the site on Friday.

A banner that reads “Strength Julen! Totalan is with you”, is seen at the area where the Spanish two-year-old boy fell into a deep well. Photograph: Jon Nazca/Reuters

Once the first tunnel is completed, rescuers will begin working by hand to construct a second shorter tunnel to reach the area where the boy is trapped, which will take a further 20 hours.

Residents of the town have held vigils for Julen and in support of his family.

Spanish media say the boy’s parents suffered another tragedy in 2017 when their three-year-old son died suddenly of health problems while walking along a beach.

“Be strong, Julen. Totalan is with you,” read a handmade banner hung on the roadside near the rescue site.

“We are living some incredibly difficult hours for relatives, friends and neighbours (of the family) and we want to send them our support in this moment,” government spokeswoman Isabel Celaá said on Friday in a news conference.