The teenagers and a 23-year-old man are being questioned after police were called by the ambulance service to an address in Darwen, East Lancashire, shortly after 4.15pm on Thursday.
A 42-year-old man who had suffered a number of stab wounds was pronounced dead at the scene in Hazel Avenue.
Police said a 42-year-old woman also sustained a stab wound and was taken by ambulance to Blackpool Victoria Hospital, where her condition is described as stable.
The suspects were arrested at an address in Frances Lane, Darwen, on Thursday.
In a statement, Lancashire Police said: “Three males from Liverpool, aged 15, 16 and 23, were arrested a short time later at an address on Frances Lane.
“They are currently in custody being questioned on suspicion of murder.” Anyone with information should contact police on 101 quoting number 0917 of August 25, or contact Crimestoppers on 0800 555 111 or online at crimestoppers.org.