Waldo county sheriff authorities say 47-year-old Ricky Pomeroy was stabbed in the back.
Police say a group led by Pomeroy went to the home of 44-year-old Kirt Damon Sr. on the Damon Road in the Cape Jellison area.
They say both sides pulled out weapons including clubs, knives and a shot gun.
Pomeroy is believed to be in serious condition at a Bangor hospital.
No arrests have been made.