Two people were killed and two others seriously injured in a house fire in Richmond Tuesday night, and a relative who also lives at the home has been arrested as a suspect.

Firefighters were initially responding to a separate house fire two doors down when bystanders alerted them to the blaze at the second home, as Bay City News reports. The fire quickly escalated to three alarms, prompting crews to redirect all available resources to the residence

Four victims were found inside, including a 47-year-old man, his 33-year-old daughter and her 5-year-old son and 2-year-old daughter. The grandfather died at the scene, while the other three family members were taken to a hospital. The boy later died, and the woman and girl remained in critical condition.

The fire was brought under control around 9:25 pm, about an hour after crews were first dispatched to the area.

As investigators worked to determine how the second fire started, they identified 32-year-old Sergio Rivera Vega as the suspect, according to KTVU. Vega is the son, brother, and uncle of the victims and also lived at the home. A detective reportedly spotted him standing behind police tape at the scene.

Vega was arrested and booked into jail on two counts of murder and two counts of arson causing injury. His bail was set at $2.5 million.

The first fire, which occurred two doors away, was also being investigated as arson, but police said it involved a different suspect and was unrelated to the deadly blaze. That fire was reported around 8:15 pm and had been brought under control shortly before 9 pm, when the second fire was discovered.

Richmond Police Chief Bisa French said the timing and proximity of the two fires made the second blaze immediately suspicious, per Bay City News.

“The second fire that was mentioned was immediately considered suspicious because it occurred only a few houses away from the first fire and began within a short period of time while emergency personnel were still responding to the original fire,” Simmons said.

A preliminary report from KTVU published before Wednesday’s press conference included an interview with a nearby resident who said there had been an ongoing conflict between the neighborhood and the resident of the house involved in the first fire, including an altercation that occurred earlier that day. That information has since been overwritten with more recent updates.   

Police said they do not believe there are any additional suspects in the second fire. Detectives are reportedly reviewing previous calls for service at the home as they investigate a possible motive.

Police also said there is no indication of an ongoing threat to the public.

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