The brutal attack happened in Cleary Crescent, Newry, Co Down.
It’s understood a 26 year old man had been assaulted with a hammer.
He was taken to hospital where he is receiving treatment.
The suspects, aged 17 and 29, were detained by police after fleeing the scene at around 12.20 am.
They remain in custody this morning.
Detective Sergeant Connor said: “Anyone with information or who may have witnessed the males leaving the area at around 12.20 is asked to contact police on 101, quoting reference 21 29/05/19.”