Police were initially called by the ambulance service to an address on Patterdale Avenue at about 7.25pm yesterday where a woman was being treated for a number of stab wounds.
She was taken to Blackpool Victoria Hospital where she is currently in a stable condition.
Enquiries revealed that the victim, 36, had been stabbed outside an address on Nun Street in Lancaster.
A man aged 47 has been arrested on suspicion of Section 18 wounding with intent and a woman aged 39 has been arrested on suspicion of attempted murder and affray.
They are both in custody.
Detective Inspector Andy Ellis, of Lancaster CID, said: “The victim in this case has received some significant injuries and I would appeal to anyone who saw anything suspicious in the area around Nun Street and Patterdale Avenue and Melbourne Road to get in touch.”
Anyone with information should call police on 101 quoting log number 1417 of August 16 or independent charity Crimestoppers on 0800 555 111.