Detectives investigating the murder of Mary-Ann Leneghan have made two further arrests.
Ms Leneghan and her 18-year-old friend, who remains seriously ill in hospital, were abducted by a gang of six men late on Friday night.
Detective Superintendent Mark Warwick of Thames Valley Police, said this afternoon's arrests marked a significant development in the inquiry.
One was arrested in London and the second in Birmingham.
A 21-year-old man who was arrested in London yesterday remains in custody and is still being interviewed.
