Officers were called to an address in Chatham Place at 5.43pm on Wednesday (December 23) where the 16-year-old boy was found with stab injuries to his chest and legs.
He was initially treated at the scene but was later transferred to hospital where he remains in a critical condition with his family by his bedside.
As the inquiry progresses, officers have today made two further arrests.
A 20-year-old man and a 28-year-old woman, both from Preston, have been arrested on suspicion of assisting an offender. They are both currently in custody.
Meanwhile, officers have been given more time by Preston magistrates to question three males who were arrested on Thursday as part of the investigation.
They are a 16-year-old boy from Preston and an 18-year-old man from Leyland both arrested on suspicion of attempted murder; and a 17-year-old boy from Preston arrested on suspicion of conspiracy to commit murder.
A 36-year-old woman from Leyland arrested on suspicion of assisting an offender has been released under investigation.
DCI Lee Wilson, of the Force Major Investigation Team, said: “This incident has left a teenage boy battling for his life and my thoughts are with him and his family at this extremely distressing time.
“While we have now made a number of arrests, our enquiries are very much ongoing.
“This appears to have been an attack on a defenceless young man and while we remain open-minded as to why this has happened, I want to appeal to the community of Preston and, in particular Deepdale, to come forward if they have any information that could assist us in bringing those responsible to justice. I want to reassure members of the public that if they come forward and assist us with any information that this will be dealt with in the strictest confidence. I would urge the public not to assume the police already know what they need in relation to this investigation and no matter how insignificant it may seem to them the information they hold could be crucial to establishing the facts of what occurred.
“There will continue to be a visible police presence in the area and reassurance patrols have been increased.”
Anyone with information is asked to call police on 101, quoting log 0575 of December 24, 2020, or report it via the major incident portal at https://mipp.police.uk/operation/0401020120S05-PO1. Alternatively call independent charity Crimestoppers on 0800 555111.