Lopez said that deputies responded and found two additional adults dead inside. Investigators believe the bodies belonged to the mother of the grandson and her boyfriend.
Lopez said that investigators suspect the boyfriend in killings and called the incident a "horrific tragedy."
NORTH CAROLINA MURDER-SUICIDE LEAVES FIVE DEAD, INCLUDING THREE MINORS: ‘SCREAMING FOR HELP’
The female victim's boyfriend is suspected to have killed her and her son in an apparent murder-suicide. (FOX35 Orlando WOFL)
Investigators had few details at the time of the news conference.
Lopez said that the family "barely knew" the boyfriend, who had been living at the residence since August.
Investigators said the bodies could have been in the home for a couple of days before they were discovered. (FOX35 Orlando WOFL)
"We don’t have a lot of info on their relationship, and we don’t have a history of any type of domestic violence between them at this residence," the sheriff said.
The bodies could have been in the residence for at least a couple of days and their conditions prevented investigators from releasing their identities, the weapon used or cause of death, Lopez said.
A medical examiner was working to positively identify the bodies and determine their cause of death.
Osceola County Sheriff Marcos Lopez told reporters that deputies received a call from the grandmother after she went to check on her grandson and found him dead. (FOX35 Orlando WOFL)
Investigators believe the grandson may have been around 21 years old while the other two victims could have been in their 40s.
A neighbor told FOX35 Orlando that the woman who lived at the residence was "a nice lady" who "never bothered nobody" and "always said hi."
"It’s crazy that nobody noticed that happened," the neighbor said.
Detectives were continuing to investigate.