A WOMAN who went missing aged 11 and was reunited with her family 18 years later is said to have had two children with her abductor, it emerged.

Jaycee Lee Dugard was snatched by two people in a car from a bus stop outside her home in 1991.

Police said they are "99% certain" the person who walked into Concord police station in California almost two decades later is Jaycee.

Speaking at a press conference, a spokesman for the El Dorado Sheriff's Department said two people were arrested on suspicion of kidnapping and other offences. They were named as Phillip and Nancy Garrido.

In a chilling echo of the Josef Fritzl case - the Austrian man who fathered seven children with his daughter while she was imprisoned in his cellar - Jaycee is believed to have had two children with her alleged kidnapper.

The spokesman said Jaycee was allegedly kept in a shed in the back garden of the Garrido's house where her children - aged 11 and 15 - were born and brought up.

El Dorado County Undersheriff Fred Kollar said Jaycee and her two girls were kept in complete isolation in a compound at the rear of the house in Antioch, California, where Mr and Mrs Garrido lived.

They appeared to be in good health, but added that "living in a backyard for 18 years had taken its toll" on Jaycee.

The children have never been to school and never been to the doctor, he said.

"The Garridos were taken into custody and an investigation led to their residence in Antioch," he said.

"Two minors turned out to be children of Jaycee and the male suspect, Garrido. They, along with Nancy Garrido, were living together at the residence in Antioch since the original kidnapping."

It also emerged that Mr Garrido was convicted of rape and kidnap in Nevada in 1971. He is being held with his wife in the El Dorado county jail.

The undersheriff described the compound where the family was imprisoned as a "series of sheds" with electricity and a "rudimentary shower".

He said: "A search of the residence revealed a hidden backyard with sheds, tents and outbuildings where Jaycee and the girls spent most of their lives. There was a vehicle hidden in the backyard that matched the vehicle originally described at the time of the abduction.

"The tents and outbuildings at the backyard were placed in a strategic arrangement to inhibit outside viewing and isolate the victims from outside contact."

He said one shed was soundproofed and could only be opened from the outside, while another had access to the back garden.

Mr Garrido, 58, and 54-year-old Mrs Garrido were arrested on suspicion of kidnapping and conspiracy, police said. Prison officials said Mr Garrido later admitted the kidnapping after meeting his parole officer.

It is understood that Jaycee and the two children were also at the meeting.

Mr Garrido is also being held for investigation of rape by force, lewd and lascivious acts with a minor and having sex with a minor, a spokesman for the Contra Costa Sheriff's Department said.

DNA tests are being carried out to confirm that the woman who walked into a San Francisco Bay area police station recently really is Jaycee.