A third person has died as the result of an alleged arson fire Tuesday night at a family home in Richmond.

Richmond police spokesperson Lt. Joe England said Thursday that a 2-year-old girl, the suspect’s niece, is now among the fatalities.

The girl had been in the hospital, along with her 33-year-old mother, who is still in critical condition, England said.

Previously reported deaths from the fire include the suspect’s 5-year-old nephew and 47-year-old father.

The suspect, 32-year-old Sergio Rivera-Vega, was arrested near the scene of the fire, which was in the 200 block of 15th Street, and was booked into jail on suspicion of two counts of murder and two counts of arson causing great bodily injury. His bail was set at $2.5 million.

A person with short dark hair and a beard wears a black hoodie and a white face mask pulled down below their chin, posing for a mugshot against a plain gray background.
Sergio Rivera-Vega, 32, was arrested on suspicion of setting a fire that killed his father, 5-year-old nephew and 2-year-old niece in Richmond, Calif. on Wednesday, Aug. 20, 2026. (Richmond Police Department via Bay City News)

Police officials said a motive for the alleged arson is still under investigation.

Rivera-Vega, who also lived in the house, is suspected of starting the fire just two doors down from another alleged but completely unrelated arson fire.

Richmond Fire Department crews were sent to the first fire at about 8:15 p.m. Tuesday. After that fire was under control at about 8:45 p.m., bystanders alerted firefighters of another fire at a nearby home, which is the one Rivera-Vega allegedly started, according to authorities.

The second fire was under control by about 9:25 p.m., according to Richmond Fire Chief Aaron Osorio.

Three of the victims were taken to the hospital, where the children died. The suspect’s father died at the scene.

All of the victims were injured or killed by the fire, and there is no evidence that they were shot or stabbed prior to the alleged arson, according to police.

No injuries or deaths related to the first fire were reported, but police did arrest a suspect in that case, and their name wasn’t released Wednesday.

Kiley Russell writes primarily for Local News Matters on issues related to equity and the environment. A Bay Area native, he has lived most of his life in Oakland. He studied journalism at San Francisco State University, worked for the Associated Press and the former Contra Costa Times, among other outlets. He has covered everything from state legislatures, local governments, federal and state courts, crime, growth and development, political campaigns of various stripes, wildfires and the aftermath of Hurricane Katrina.