One of the injured, a 20-year-old man, is in critical condition with burns and smoke inhalation.
Arson and homicide investigators were called to the scene of the blaze at the student-rented house near Ohio State University. Police Sgt. Dana Norman says detectives are investigating reports that a fight had started before the fire ignited.
"The cause has been ruled suspicious," says Fire Department spokeswoman Kelly McGuire.
Party guest Richie Delmont, an Ohio State junior, says an argument started after another guest tried to lift a refrigerator on a dare and one of the residents told him to stop. He said the confrontation did not get physical.
The house is about a block from campus in a neighborhood of older homes popular with students. About 80 people had been at the party, and 10 to 20 were still inside when the fire started around 4 a.m. in the front of the house, according to police.
Firefighters found two men and three women dead inside; the women were Ohio University students and the men attended Ohio State. Police say it appears that some of the victims were asleep when the fire started.
Police also say alcohol could have been a factor in the deaths and injuries.
"The smoke and gases from the fire are extremely deadly and when you're drunk or have been drinking that also contributes to slowing down your reaction time," says Police Sgt. Dana Norman.
Autopsies are planned. Franklin County coroner Dr. Brad Lewis said the victims appear to have died from smoke inhalation and carbon monoxide poisoning.
University President Karen Holbrook spoke with investigators outside the house after a private briefing with fire and police officials earlier in the day.
"We are clearly a community in mourning," Holbrook said.
Of the 12 Ohio State students who lived in the house, ten got out alive, said one of the residents, Zack Randol, 21, a sophomore from New York who said he wasn't home at the time of the fire.
He said the party was to celebrate the 21st birthday of one of his roommates. "This is the worst thing that could happen," said Randol.
Jennifer Lehren said she and her boyfriend had been asleep in his bedroom at the back of the house on the second floor, and she woke up while firefighters were carrying the two of them to safety.
"I didn't know what was going on until I was outside," said Lehren, 20. "I remember screaming that it was so hot and that my hair was on fire."
Lehren was treated for burns on her hands and released. Her boyfriend, Josh Patterson, 20, is in critical condition with minor burns and smoke inhalation.
About a dozen students who said they knew the men who lived in the house gathered on a nearby street corner Sunday afternoon.
"They're not wild. They don't have people over who would do this. They don't have enemies. They're not those kind of guys," said Tomomi Ono, 19. She said there were four kegs and at least a dozen cases of beer at the party.
By Liz Sidoti