Homicide detectives are on scene at a motel in National City after the bodies of one adult and two older children were found along with a handgun.
According to police, the bodies were found around 10 a.m. Tuesday morning at the Paradise Motel on National City Boulevard.
A female relative called police and asked for them to conduct a welfare check at the motel.
An 11-year-old girl and a 16-year-old boy are among the dead along with an adult male with what police believe to be a self-inflicted gunshot wound.
Police say they are investigating this as a murder-suicide and believe all three are related.