A 32-year-old Richmond man has been arrested on suspicion of murder and arson after a fire that police say was deliberately set killed his father and 5-year-old nephew and left his sister and 2-year-old niece in critical condition.
Officers first responded to the 200 block of 15th Street at about 8:16 p.m. Tuesday to assist Richmond Fire Department crews with a residential structure fire, according to the police department.
About 30 minutes later, at 8:47 p.m., while emergency crews were still at the first fire, Richmond Fire notified police dispatch of a second residential fire about two houses away.
Police are treating both fires as arson, Lt. Joseph England, the department's public information officer, said. The first fire remains under investigation as detectives work to determine its cause. The second fire is being investigated as both arson and murder. Police had not determined a motive as of Wednesday afternoon.
"As of right now, it's all being investigated," England said when asked about a possible motive.
"This unimaginable tragedy has taken the lives of a man and a young child while leaving a woman and another young child fighting for their lives," police said in the release. "The Richmond Police Department and Richmond Fire Department extend their deepest condolences to the victims, their loved ones, and everyone affected by this devastating incident."
"A 5-year-old should not be dead," England said at the news conference. "A 2-year-old should not be in critical condition right now."
Grandview IndependentSoren Hemmila
Firefighters who arrived at the second home 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.
The 47-year-old man died at the scene despite efforts by emergency personnel, police said. The other three victims were taken to hospitals. The 5-year-old boy later died. The 33-year-old woman and 2-year-old girl remained hospitalized in critical condition Wednesday, police said.
Because the second fire broke out only two houses from the first while firefighters were still on scene, police immediately treated it as suspicious. Homicide detectives and Richmond Fire Department arson investigators responded and began working the scene.
Detectives identified the suspect as Sergio Rivera-Vega, 32, a relative of the victims who lived at the home, according to police who would not discuss the evidence that led them to Rivera-Vega.
As detectives continued working the scene, one of them spotted Rivera-Vega standing behind the yellow police tape. He was taken into custody without incident.
"As our detectives were on scene, one of our detectives saw the suspect standing behind a yellow tape at the scene, so he was safely taken into custody and arrested," England said.
Rivera-Vega was booked into the Richmond Police Department jail on suspicion of two counts of murder under Penal Code section 187(a) and two counts of arson causing great bodily injury under section 451(a). His bail was set at $2.5 million.

Police said they believe the person responsible for the fatal fire is in custody and that there is no ongoing threat to the public.
Richmond Fire Chief Aaron Osorio said the department responded to the second fire with the El Cerrito Fire Department and Contra Costa County Fire Protection District. The fire was elevated to a third alarm, with about 35 firefighters on scene at its peak, not including command and investigative staff.
Osorio said initial reports indicate the fire was already well involved when crews arrived, with flames coming from the front door and windows.

A woman whose name has not been released was arrested in connection with the first fire, which caused no injuries and remains under separate investigation. Police said there is no evidence linking the two suspects or the two households.
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