A 21-year-old man has been arrested on suspicion of murder after two teenagers were fatally stabbed at a house party in Milton Keynes, Thames Valley Police said.
Thames Valley Police said he was arrested on Monday evening and remains in custody.
Although formal identification has not yet taken place, the victims have been named locally as 17-year-olds Dom Ansah and Ben Gillham-Rice.
Both teenagers 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.
The two close friends were attending a private party at a house on Archford Croft, in the Emerson Valley area of the town, when they were attacked.
Police previously said the 15 to 20 people attending the birthday party, believed to have been held by a girl who lived in the house, were all known to each other.
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.
A neighbour who knew the victims suggested the incident was related to a house party which had been held in the vicinity, with another neighbour saying she heard a “commotion” involving screaming shortly before midnight but did not see what happened.
“The police were here pretty quick,” she said.