Officials say the fire yesterday inside the home in Tampa's exclusive Avila neighbourhood was intentionally set.
Hillsborough County Sheriff's Col Donna Lusczynski said Blake rented the home to the Campbell family.
Voter registration records identified them as Darrin Campbell and his wife, Kimberly, but investigators say they won't know the victims' identities until preliminary autopsies are completed.
Officials say the Campbells were unaccounted for yesterday.
Lusczynski described the fire as unusual and said there were "various fireworks" throughout the home. Two victims suffered from upper-body trauma, but Lusczynski didn't indicate which ones or provide other details. She also said no weapons had been found at the home and that murder-suicide was a possibility.
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"They were a very nice family, we know nothing of any problems," Connley said. "The kids were outstanding children. This is very difficult to put our arms around."
He said that Kimberly Campbell was "sophisticated and classy."
The fire at the 557-square-meter home north of downtown Tampa was reported about 6 am yesterday.