Jeanette Ogara was pronounced dead at the address in the 24000 Potrero Valley Road at 1:24 a.m. Tuesday, according to the county Medical Examiner's Office.The Medical Examiner's Office has yet to release an official cause of death although sheriff's officials said the victim died of shrapnel wounds.The death was reported just after midnight Tuesday, sheriff's officials said. The couple's 4-year-old daughter and three adults who were in the trailer with the victim at the time of the fatal blast were unharmed, sheriff's Sgt. David Martinez told reporters Tuesday. The girl was turned over to child protective services personnel.Medics took the woman's boyfriend, Richard Dale Fox, 39, to Sharp Memorial Hospital in San Diego for treatment of leg injuries he suffered when the makeshift mortar went off.Fox was then arrested and booked into county jail on suspicion of detonating an explosive device in a manner resulting in death, Martinez said.The suspect's motivation for allegedly firing off the weapon in the direction of his residence was unclear, according to Martinez.Preliminary evidence suggested that Fox had been drinking prior to the deadly blast, Martinez told news crews.The sergeant said he did not have a detailed description of the home-constructed cannon, though he said the suspect apparently had used explosive powder from fireworks to shoot it. The type of projectile that was fired into the mobile home also was not immediately clear.