"There is no indication it was suicide. It looks like it was accidental," said Lt. Susan Benton of the Highlands County Sheriff's office.
Two of the victims were found in a truck in the garage with the radio on, Benton said.
"It's my understanding from the father of two of the children that it was not uncommon for someone in the family to sit in the truck and listen to the radio with the engine running," she said.
Investigators had not yet determined the relationships between the victims. The children ranged in age from 4 to 12-years-old, Benton said.
Family members told police they talked to their relatives on Friday, Benton said.
Neighbors said the family who lived in the house was Hispanic and owned a grocery store in the town. The family moved in this past December.
Lake Placid, with only about 1,200 people, is 80 miles southeast of Tampa and 90 miles northwest of West Palm Beach.