The sheer number of young victims who were unable to escape a burning home, even with a warning from a smoke detector, led authorities to investigate whether the blaze had been set, the city fire chief said Wednesday.

Tests later found the presence of an accelerant, confirming the fire was arson, authorities said.

"We had young, able-bodied people who we believe had a smoke detector warning and weren't able to evacuate. I think that got our attention the most," Chief Paul Stubbs said at a briefing Wednesday.

At first, investigators thought the May 21 fire that killed nine, eight from one family, was accidental, Stubbs said. Hours after the tear-filled funeral Tuesday for the eight family members, the mayor told relatives that investigators determined the fire was arson.

The victims were attending a sleepover when the fire broke out. All nine died of smoke inhalation on the second floor of the wood-frame house. A person normally would have 3 to 4 minutes to escape in that situation, Stubbs said.

Fire debris sent to a state lab determined an accelerant was used, he said. He would not say what type of accelerant was use or where the fire started.

No arrests have been made and Stubbs would not comment on whether officials had any suspects. Various people are being interviewed about the case, Stubbs said.

One man escaped unharmed from the fire, and one woman survived but was critically burned. Her condition was later upgraded to fair.

Mayor Jane Campbell (search) said she met with family members of the victims Tuesday night.

"They said they had some suspicions there was something wrong, but they also said they were so sorry to hear it was intentional and none of them could imagine what would compel someone to do this, especially to children," she said.

"I had to tell the family," she told told WEWS-TV. I didn't want them to hear it from the media, I wanted them to hear it from me."

Fannie Cockfield, great-grandmother of 13-year-old victim Miles Cockfield, a friend of the other children who lived in the house, expressed anger.

"Whoever is responsible really should be buried," she said. "He should not be allowed to see the light of day after so many people died."

Police Chief Michael C. McGrath, who attended the two-hour service Tuesday at the Cleveland Convention (search) Center, estimated the crowd at 4,000. The 67,000-student Cleveland school system, Ohio's biggest, was closed for the day so classmates and teachers could attend the service.

"I've never seen nothing so sad in my life," said Robert Ivery, 34, who grew up with Carter and knew her children. "For so many homes and families and hearts to be touched in the way that they have with so many losses."

Campbell led the mourners in applauding firefighters, EMS crew members and police officers who responded to the fire and said the tragedy had unified the city.

"This has been an extraordinary effort by this community," she said.

Some caskets were decorated with stuffed animals and all eight were adorned with flowers.

"I love you all," said Evelyn Martin, mother of Medeia Carter, 33, who died in the fire with four of her six children. "I am grateful to God that she went with the babies and the babies went with her."

In addition to Carter and Miles Cockfield, the fire killed Earnest Tate Jr., 13; Devonte Carter, 15; Maleeya Williams, 12; Fakih Jones, 7; Antwon Jackson Jr., 14; Shauntavia Mitchell, 12; and Moses Williams Jr., whose sleepover was to celebrate his 14th birthday.

Burial for all nine was arranged at Whitehaven Memorial Park in suburban Richmond Heights (search) in plots donated by a retired police detective and the cemetery.