Firefighters had not determined the cause of the blaze by midday Wednesday. However, authorities said they did not believe the fire was suspicious and may have started in the bathroom area next to the furnace.
The blaze at the Rolling Hills Mobile Home Park, about 15 miles west of Syracuse, was reported just after midnight.
The children's mother, Teri Carson, was not home but had left her 15-year-old daughter, Lori Carson, to watch the younger children, authorities said.
State Police Lt. Erwin Brandl said Teri Carson, 37, was visiting a friend. All five children were sleeping when the blaze started and Lori was awakened by smoke and flames, Brandl said.
Lori escaped from the burning house and alerted neighbor Andy Keegan, who rushed to the scene and pulled 8-year-old Tamarah Houghton, the triplets' half-sister, out through a window, authorities said.
Tamarah was in critical condition at University Hospital in Syracuse, authorities said.
Keegan was unable to reach the triplets, a girl and two boys identified as Paige, Alex and Allen Hendershot
