(CNN) — a Family of six has been discovered on a remote farm in the Netherlands where they are believed to have lived in isolation for nine years, according to CNN affiliate NOS.

The father and five children, aged between 18 and 25, were found in the small village of Ruinerwold, in the northeastern province of Drenthe, Dutch police told CNN. The sixth adult child left and was the one who alerted the police.

Although the village has only a few thousand inhabitants, no one knew that the family was there.

Police arrested a 58-year-old man who rented the property. Authorities said they are still trying to establish a connection between the detained man and the family, and they believe the family has been living there since 2010.

For nearly 10 years, the family lived indoors and did not go outside until this month, when the eldest son left, according to NOS.

The son visited one of the village’s few cafes, Caf de Kastelein, looking fresh and untidy, nos reported. He came in and tried to order a beer one night but left as the cafe was about to close, cafe owner Chris Westerbeck told RTL Germany. He came again one more night, but quickly left.

Westerbeck described him as having long hair, a long beard, and dressed in old clothes, reports NOS.

“Last Sunday he came and he was sitting here on the terrace and he asked for help,” Vesterbeck told RTL Germany. “So I tried to talk to him, didn’t get enough information about him, so I asked him to call the police, the police, so we could help him further.”

Son said Westerbeck he had never been in school and haven’t been to the Barber in nine years, in accordance with NOS.

In a statement Tuesday, local police said they went to the family’s home after the eldest son said, ” He was concerned about his family’s living conditions.”

An investigation is underway

A team of investigators scouted the area, surveyed the area and even used a drone to map the house from above before entering and finding the family inside, local police said.

“It is unclear whether they remained there voluntarily,” police said in a statement.

The family was not registered in the state archives. They have now been examined by doctors, police said.

“Part of our investigation is to find out what the people in this house were doing exactly. There are many more questions that we don’t have an answer to. The investigation is ongoing. People have been taken to a shelter where they will be cared for and where they will be asked to tell their story, ” police spokeswoman Natalie Schubart told rtL Netherlands.

Ruinerwold mayor Roger de Groot spoke to the media on Tuesday, saying he had “never experienced anything like this.” He added that investigators believe the mother in the family died several years ago, possibly before the family moved to the farm.

According to NOS, the family had no contact with the outside world during those nine years.

Dutch police said they found them in a small room on the ground floor. Aerial photos of the property show a manicured garden with what appear to be vegetables planted in neat rows, and the NOS reported that the family also goats.

Aerial photos of the hotel show three roofs. Some of the doors of the buildings are covered with overgrown greenery.

The house was accessible by a bridge over the river that neighbors said was always closed and locked, NOS reported. One neighbor told NOS he once tried to approach but turned back when he saw several cameras on the property.

Neighbors said they never saw the children – only one person who regularly drove by in a car, according to the NOS.

“We understand that everyone still has many questions. We have those, too, ” Dutch police said in a statement, adding that they have appointed a large team to investigate how the family ended up there and whether any crimes were committed.

He will appear in court on Thursday and is suspected of involvement in unlawful imprisonment and causing injury to others, the regional Prosecutor told aimu on Twitter.

CNN’s Roseanne Roobeek, Stephanie Halasz, Carly Wilson, Valeria longi and Phillip Victor contributed to this story.