SAN DIEGO—Police are treating a fire at the home of a San Diego County leader and his wife, a prominent labor official, as suspicious. County Board of Supervisors Chair Nathan Fletcher said he and wife Lorena Gonzalez and their family were awoken by smoke alarms around 4 a.m. on Wednesday. “The front of our house was engulfed in flames, but we were able to safely evacuate out another door,” Fletcher said in a statement. The fire caused about $30,000 of damage to the house and another $6,000 in damage to a vehicle parked in front, said Monica Muñoz, spokeswoman for the San Diego Fire-Rescue Department. Specially trained police and fire investigators with the San Diego Metro Arson Strike Team were called to the scene, a Police Department statement said. The “fire is being treated as suspicious in nature,” it said. Police officers were quickly on the scene and firefighters saved …