One victim, Donald Knight, ran into the house to try to rescue his nephew and the others, said his brother, James Knight.
"The whole house was engulfed. The whole house was nothing but red," James Knight said.
Investigators did not know what caused the fire, which took 40 minutes to extinguish. Authorities said they plan to investigate whether holiday decorations or candles were involved.
Neighbors also tried to help after the fire started, including a man who used a garden hose to spray the flames and another man who tried to go inside but was turned back at the front porch steps, residents said.
Joyce Hodous, who lives three houses down the street, said she was awakened by yelling at about 4 a.m., after firefighters had arrived.
"There were children screaming to get out, 'Please, help me!"' she said. Firefighters were already at the scene, she said.
Two adults and a child pulled from the first floor died at the house, said Battalion Chief Raymond Harple. Three others, found on the second floor, were pronounced dead at hospitals.
A seventh person, 21-year-old Nicole Cavanaugh, died Tuesday night in the burn unit at Akron Children's Hospital.
Besides Donald Knight, 43, his nephew, Jerry Knight, 9, and Cavanaugh, the victims were identified as Dale Gross, 34; Leigha Gross, 10; Cally Gross, 4; and Katlin Cavanaugh, 7 weeks. Authorities were trying to determine the victims' relationships.
Jerry Knight was visiting the home, said his uncle, James Knight.
"They were all like family. We were all friends of the family. We weren't biological, but we're all family," he said.
The home apparently had no smoke detectors, officials said.
In heavy rain, several weeping people placed teddy bears and red, green and pink balloons near the house. A pink backpack lay on a heap of charred debris.
Canton is 50 miles south of Cleveland in northeastern Ohio.