VALLEJO (CBS SF) — A man fatally shot his ex-girlfriend and their 4-year-old son before turning the gun on himself in a domestic violence incident in Vallejo on Thursday night, police said.

The suspect is identified as 25-year-old Jacoby Brandon Brooks of Vallejo. At around 11:52 p.m. Thursday, officers received reports of an unresponsive woman at the intersection of Lewis Brown Road and B.W. Williams Drive in Vallejo.

Police located the victim, a 26-year-old Vallejo resident, dead at the scene from at least one gunshot wound. Her identity is being held until the notification of next of kin by the Solano County Coroner’s Office.

Detectives learned that the victim was a mother to a 4-year-old boy and their investigation led them to the 500 block of Quartz Lane. There, they found the son dead with at least one apparent gunshot wound. Police obtained an arrest warrant for Brooks on two counts of murder.

But a short time later, officers located Brooks nearby the Quartz Lane crime scene. He was dead from a self-inflicted gunshot wound.

Investigators learned that Brooks and the adult female victim had a prior romantic relationship and they also believe that Brooks is the father of the 4-year-old.