London (CNN) -- British police have arrested a couple on suspicion of holding three "extremely traumatized" women captive for more than 30 years, Scotland Yard announced Thursday.
One of the women -- a 30-year-old Briton -- "appears to have been in servitude for her entire life," Metropolitan Police Detective Inspector Kevin Hyland said. She and the other two women, a 57-year-old from Ireland and a 69-year-old from Malaysia, have been taken to a place of safety and are being cared for by a charity, police said.
The man and woman in custody are both 67, police said. They were arrested at their home in the south London borough of Lambeth and are being held as part of an investigation into slavery and domestic servitude, police said. Their names were not released, and police said only that they are not British nationals.
Hyland said it was an unprecedented case for the Met's Human Trafficking Unit.
Police said they'd been alerted in October to the situation by Freedom Charity, which got a phone call from a woman saying "she had been held against her will in a house in London for more than 30 years." Freedom Charity spokeswoman Aneeta Prem said the organization had taken "immediate action" to plan a rescue after learning of the women's situation.
"Facilitating their escape was achieved using utmost sensitivity and secrecy and with the safety of the women as our primary concern," she said, describing the work of those involved as "outstanding."
UK Special Envoy for Human Trafficking Anthony Steen told CNN he was not surprised by the case as there were likely to be many cases of domestic slavery in the country.
"We don't know the number but we know it's pretty huge. Domestics are hidden away," he said.