VISTA–Three people found dead in a Vista home were allegedly shot to death, according to homicide detectives.

On March 12, at approximately 10:45 p.m., San Diego Sheriff’s Deputies responded to a radio call of a fight in the 1400 block Phil Mar Lane in Vista.

Upon arrival, deputies contacted the occupants of the residence and the individual who called the Sheriff’s Department. All of the individuals on scene were uncooperative and refused to provide deputies with any information about the fight, according to investigators.

Deputies detained a 53-year-old man as he was driving away from the residence. He stated that  he had just left his ex-girlfriend’s residence on Phil Mar Lane after he was involved in a physical altercation with her brother. The man had minor visible injuries that he stated were incurred during the altercation and deputies ultimately determined he was the victim of an assault.

After further investigation, deputies determined he was driving under the influence of alcohol and he was arrested. He was transported to the Vista Patrol Station for processing and paramedics responded to evaluate his injuries; he ultimately refused medical treatment. Due to the injuries the man sustained during the assault, he was released on his own recognizance at approximately 1 a.m.

On Monday, at approximately 5:33 a.m., Sheriff’s deputies again responded to the residence. The reporting party told dispatchers she arrived at her friend’s home and found three people dead inside. Deputies arrived on scene and located three people who were deceased with apparent gunshot wounds.

The preliminary investigation indicated the assault victim returned to the residence on Phil Mar Lane where he shot and killed his ex-girlfriend and her brother before killing himself.

The Medical Examiner’s Office will be conducting an autopsy and will confirm the cause and manner of the deaths.

The investigation is ongoing.