Rescuers in southern Spain are racing to reach a toddler who fell down a borehole more than 100 metres deep four days ago.

Two-year-old Julen Roselló had gone for a picnic with his family in the countryside on Sunday when he fell down the 25cm-wide hole in Totalán, near Málaga.

He has not been seen or heard from since the fall, but relatives and rescuers are desperately hoping he is still alive.

Engineers and specialist miners are lining the borehole to prevent it from collapsing and have sunk parallel and horizontal shafts into the hillside to try to locate Julen.

For now, they are focusing on the vertical shaft as the quickest way to gain access.

A tunnel-drilling machine arrives to bore into the hill to where Julen Roselló is assumed to be located. Photograph: Alvaro Cabrera/EPA

Juan López Escobar, a representative of Málaga’s mining college, told reporters it could take two or three more days to reach Julen.

“Under normal conditions, you’d do a planned project using samples and soundings, and the work would take a month,” he said. “But in this case, the urgency of the rescue means a different timetable.”

López Escobar said talking about timeframes was unhelpful. “We’re working to do it as soon as possible because of the health of the child.”

Guardia Civil police officers and firefighters are being assisted by a team of mine rescue experts from Asturias and members of the Swedish rescue firm that helped find the 33 Chilean miners who were trapped underground for 69 days in 2010.

On Wednesday, regional authorities said a hair sample had been recovered from deep inside the shaft that matched Julen’s DNA.

Two days earlier, rescuers exploring the hole found the cup and packet of sweets he was holding when he disappeared.

Efforts to get to the toddler have been thwarted by a compacted plug of hard soil under which he could be trapped.

The child’s father, José Roselló, said he had rushed to the hole as soon as he heard him cry out.

“I pushed the stones away and heard my son crying,” he told the local Sur newspaper.

“My son is down there – don’t let anyone try to cast doubt on that. I wish it were impossible for him to be down there, but I heard him. I wish it were me buried down there so that he could be up here with his mother.”

Totalán residents march in support of Julen Roselló and his family. Photograph: Alvaro Cabrera/EPA

Residents of Totalán held a vigil to support the family on Wednesday night.

Some held homemade placards saying “All of Spain is with you”, and, “We are sending you our strength”. One man’s sign simply read “Julen”.

“We are not only giving voice for all the residents of Totalán but also for the rest of the country because we have all had Julen in our minds since last Sunday,” Patricia Calderon, a resident, told Reuters.

According to Spanish media reports, Julen’s older brother, Óliver, died of a sudden heart attack at the age of three, while walking with his family on a beach in Málaga in 2017.

El Confidencial said Óliver had collapsed three weeks earlier but that his heart condition had gone undiagnosed.