A man was arrested on suspicion of murder and arson after a Richmond house fire killed a 47-year-old man and 5-year-old boy, police said, adding a woman and child were also critically hurt in the blaze. Firefighters initially responded to a separate fire on the 200 block of 15th Street at about 8 :08 p.m. Tuesday. The blaze, which is also being investigated as an arson, was declared under control just before 9 p.m., and its cause remains under investigation. No one was injured. About 45 minutes after the initial response, while crews were mopping up the first fire, they noticed smoke and flames coming from a home two doors north. The second fire was upgraded to three alarms due to its significant size and the resources needed to respond to the number of victims, fire officials said. Richmond firefighters were assisted by crews from the El Cerrito Fire Department and Contra Costa County Fire Protection District. Firefighters entered the second home and found four people inside, officials said. The 47-year-old man and 5-year-old boy died as a result of the fire, while a 33-year-old woman and 2-year-old girl remained in critical condition. “This is an absolute, unimaginable tragedy,” Richmond police Chief Timothy Simmons said. “It has taken the life of a man and a young child while leaving a woman and another young child literally fighting for their lives.” Despite the location and timing of the two suspected arsons, police said they’re not related. Witnesses said the man who died was seen helping people at the scene of the first fire. “He was helping,” witness Armando Lara said. “So everything got under control. He just went back inside. When the next fire started, that was weird. Nobody screamed ‘Fire!’ They didn’t come out from the back door or anything.” Detectives with the Richmond Police Department’s homicide unit began investigating after the second fire started. During the investigation, detectives identified 32-year-old Sergio Rivera-Vega as the person suspected of intentionally setting the second home on fire, police said. Rivera-Vega is a relative of the victims and lived at the home. Police said Rivera-Vega was found near the scene and taken into custody without incident. “As our detectives were on scene, one of our detectives saw the suspect standing behind our yellow tape at the scene,” Richmond police Lt. Joseph England said. Lara, who also owns a restaurant nearby, shared video footage he said showed Rivera-Vega moments after the deadly fire broke out. Lara said the footage showed Rivera-Vega flipping over his restaurant’s bench. Lara also claimed Rivera-Vega tried to set his restaurant on fire last month. Police did not comment on that allegation. “[Rivera-Vega] was frustrated, like he know he did something wrong,” Lara said. “I feel bad for the family.” Rivera-Vega was booked into jail on two counts of murder and two counts of arson causing great bodily injury, according to police. His bail was set at $2.5 million. In the first fire, a neighbor provided surveillance video that showed a woman, believed to be a tenant, walking away from the home with a cart full of items moments before flames erupted. Police made an arrest but did not immediately provide information on the suspect. The homeowner, who did not want to be identified, believes the tenant set the fire, adding that police had been called to investigate her several times. Because both fires are considered suspicious, arson investigators, along with the Richmond Police Department and the Contra Costa County Sheriff’s Office, are investigating. ...read more read less