Two 17-year-old boys have died after a stabbing at a house party. The two victims have been named locally as Dom Ansah and Ben Gillham-Rice.
One of the boys died at the scene, while the other was taken to hospital but died in the early hours of Sunday.
Another 17-year-old and a 23-year-old were seriously injured after the stabbing late on Saturday night at a private house party in Archford Croft in Emerson Valley, Milton Keynes.
Detective Chief Superintendent Ian Hunter said there had been around 15 to 20 people at the party and that "the people directly involved in this incident are all likely to have known each other".
What appeared to be blood was smeared across the front door of a house in Archford Croft in Emerson Valley, Milton Keynes.
Two forensic officers could be seen inspecting an object on the driveway next to a black BMW.
One neighbour told ITV News they had not seen anything on Saturday night, but had heard loud music playing.
Another said she heard a "commotion" involving screaming shortly before midnight but did not see what happened.
"The police were here pretty quick," she said
Another neighbour, who lives in an adjacent cul-de-sac, said that she know the boys but declined to give their names.
She said: "We do know that there was a house party at the time, not here but another part of Emerson.
"I think it's just because there was a house party and then the trouble started from there."
She said of the two boys: "I think they were friends but that's all we know.
"It's just because our kids all go to the same school together."
Another woman who lives opposite the cul-de-sac said she heard: "A little bit of music last night but that's it."
Another neighbour said he had seen an altercation and was being treated as a witness by police.
One woman, whose home overlooks the property's garden, said she did not see or hear anything and described the neighbourhood as "peaceful".
"It's just a nice peaceful part of Milton Keynes.
"There's never been any incidents, not since I've been here, which is quite a while now," she said.
Detective chief superintendent Ian Hunter said: "Thames Valley Police is in the early stages of a double murder investigation after two teenage boys have tragically died in this shocking incident.
"Our priorities at this time are to conduct a thorough investigation and to support those who have been affected.
"Officers are currently at the scene which has been cordoned off and members of the public are asked to avoid the area.
"I would like to speak to anyone who has any information which could help with our inquiries or anyone who witnessed any suspicious activity in the area of Archford Croft at around the time of the incident around midnight.
"Even if you think details may be insignificant, please come forward and speak to police."
Anyone with information should contact police on 101 quoting crime reference 1761 of October 19.
Alternatively information can be given anonymously to Crimestoppers on 0800 555 111.