A man has been arrested on suspicion of murder after two teenagers were fatally stabbed at a house party in Milton Keynes.
The 21-year-old man was arrested on Monday night on suspicion of two counts of murder and two counts of attempted murder after two 17-year-olds were stabbed shortly before midnight on Saturday.
One died at the scene while the other was taken to hospital but died in the early hours of Sunday.
Formal identification has not yet taken place, but the victims have been named locally as Dom Ansah and Ben Gillham-Rice.
The close friends were attending a private party at a house in Archford Croft, Emerson Valley, when they were attacked, Thames Valley Police said.
Officers previously said the 15 to 20 people at the birthday party, believed to have been held by a girl who lived in the house, were all known to each other.
Investigating officers believe the attackers were not invited to the party, but were known to the victims.
Detective Chief Superintendent Ian Hunter said: “Although we believe that all of those involved were known to each other, we believe that those responsible arrived at the party uninvited, wore face coverings and they were armed with knives in what appears to be a targeted attack.”
A 17-year-old boy and a 23-year-old man who also suffered knife wounds were taken to hospital with serious but non-life-threatening injuries.
The 17-year-old has since been discharged from hospital and the 23-year-old is recovering well, police said.
Police, including specialist forensics officers, expect to remain on the scene for a number of days and have increased patrols in the Emerson Valley area.
Formal identification of both teenagers and a Home Office post-mortem examination are expected to take place on Tuesday.
The 21-year-old man remains in police custody.