Police arrested Sergio Rivera-Vega after the blaze killed his father and young nephew and critically injured his sister and niece.
RICHMOND, CA — A 32-year-old Richmond man has been arrested on suspicion of murder and arson after authorities said he deliberately set a house fire that killed his father and 5-year-old nephew and left two other relatives critically injured.
Sergio Rivera-Vega was taken into custody near the scene of the Aug. 18 fire in the 200 block of 15th Street, according to Richmond police. He was booked on two counts of murder and two counts of arson causing great bodily injury. Authorities said his bail was set at $2.5 million. The accusations have not been proven in court.
The fatal fire was the second of two residential fires reported within about half an hour on the same block Tuesday night. Police said officers initially responded at about 8:16 p.m. to assist Richmond Fire Department crews with a fire at one home. At about 8:47 p.m., emergency personnel were alerted to another fire roughly two houses away while crews were still dealing with the first incident.
Firefighters entered the second home and found four people inside: a 47-year-old man, a 33-year-old woman, a 5-year-old boy and a 2-year-old girl. Emergency crews provided medical aid, but the 47-year-old man died at the scene. The woman and two children were taken to hospitals, where the boy later died. The woman and 2-year-old remained hospitalized in critical condition as of Wednesday.
Police identified the dead man as Rivera-Vega’s father and the 5-year-old as his nephew. The injured woman is Rivera-Vega’s sister, and the 2-year-old girl is his niece. Authorities had not publicly released the victims’ names. Officials said the precise causes of the two deaths remained subject to further examination.
Richmond Police Chief Timothy Simmons said investigators immediately considered the second fire suspicious because it began only a few houses from the first blaze and while emergency personnel were still working nearby. Homicide detectives joined fire investigators, interviewed people at the scene and collected evidence. Police said Rivera-Vega, who lived at the home, was identified as the suspect and was arrested without further incident.
Investigators do not believe the two fires were connected. Police Lt. Joseph England said authorities considered them isolated incidents and had found no evidence linking Rivera-Vega to the first fire. Richmondside reported that a woman was arrested in connection with that earlier blaze, but police had not publicly identified her, and the circumstances surrounding that fire remained under investigation.
Fire officials said the second blaze grew into a three-alarm response that brought additional resources to the neighborhood, including personnel from other area fire agencies. Police said there was no continuing threat to the surrounding community once the fires were brought under control and the suspect in the fatal blaze was taken into custody.
The two deaths were Richmond’s sixth and seventh homicides of 2026, according to police statistics cited by Richmondside. Authorities said detectives would continue working with the Richmond Fire Department and the Contra Costa County District Attorney’s Office to examine evidence and determine the full circumstances surrounding the fatal fire. Details about Rivera-Vega’s arraignment had not been publicly released as of Wednesday.
Author note: Last updated August 20, 2026.