The first fatality occurred around 3:30 p.m. Saturday on Pennesseewasee Lake in Norway.
Wardens said 51-year-old Gracie Herrick Onofrio of Norway hit a snowbank and was thrown off. They said a second snowmobile from the party then struck Onofrio and she was pronounced dead at the scene.
The second incident occurred on Thompson Lake in the area known as Heath in Poland just before 11 p.m. on Saturday.
Wardens said 17-year-old Troy Marden of Massachusetts failed to negotiate a corner, struck a snowbank and was ejected from the snowmobile he was operating.
They said the second snowmobiler attempted to give aid before getting help.
Marden was pronounced dead at the scene.
The Maine Warden Service reminds all snowmobile operators to be mindful of their surroundings, manage their speed when operating on lakes and anticipate ridges or other obstacles that may be present.
Wardens said snowmobile traffic will be increasing during this school vacation week.