But officials with the Pasco County sheriff's department believe the whole incident may started somehow over a fight over food Wednesday night, The Associated Press reported.
Police said in a news conference Thursday that the 16 and 13 year olds were preparing food when the argument broke out Bay News 9 in Tampa reported.
CNN reported the oldest of the four brothers, who is 18, as well as the boys' mother, were not home at the time.
Meanwhile, WFLA reported grief counselors were at the boys' schools to help classmates and teachers who were rocked by the news.
School Superintendent Kurt Browning spoke with the 6-year-old's teacher, telling WFLA that "Obviously she was very emotional, very upset. Crying, as I would be crying. And as I was talking to her fighting tears back myself. I don't know these kids, but I will tell you as superintendent, it's hard not to have these, my kids."
Classmates in the youngest brother's class were told that something "very sad" happened, WFLA reported.