The Polk County Sheriff's Office said they received multiple 911 calls around 4:30 a.m. about a shooting on Divot Lane.
When first responders arrived, they found 34-year-old Jesus Nunez dead on the front walkway of the home from an apparent self-inflicted gunshot wound to the head.
Investigators then found two other victims in the home: a 36-year-old man identified as Yunieki Luis, and a 38-year-old woman, Stephanie Ruiz.
Seven children and another adult had fled the scene when the shooting began, the sheriff's office said.
According to investigators, Nunez and Ruiz have been dating for about 14 years and have four children together.
On Saturday, family members and friends had come over to their home, where witnesses said Nunez drank alcohol and used cocaine most of the day, becoming increasingly angrier until the late evening.
Family and friends told the sheriff's office the Nunez's anger and behavior usually escalated when he was drinking and using cocaine. They also told detectives that he had been suspicious and paranoid about his relationship with Ruiz, and had been very controlling.
Around 4:30 Sunday morning, one of the witnesses was awakened by the sound of gunfire. The witness ran out of the bedroom and saw Nunez screaming at Luiz, then watched him shoot him in the living room. She ran back into the bedroom, called 911, grabbed her three children and fled the home.
Detectives said after shooting Luis, Nunez broke down the door into the bedroom where Ruiz was and fatally shot her. They said evidence showed he then went outside and shot himself in the head.
"When you combine excessive amounts of alcohol, illegal drugs, and an explosive jealous temper, murder can occur," Sheriff Grady Judd said in a statement. "In addition, there are seven children and other family members whose lives will never be the same. None of this should have ever happened. Please keep these families in your prayers."
Autopsies will be conducted to determine the exact causes of death, but investigators said this appeared to be two homicides committed by Jesus Nunez, who then shot and killed himself.