Authorities say a second boy has died after his family 's car plunged into Los Angeles harbor , killing his 13-year-old brother . The family had left a waterfront restaurant Thursday night when their sedan ran off the road alongside a working dock at the Port of Los Angeles , landing upside down in about 30 feet of water . The boy 's parents swam to the surface , but the children were stuck in vehicle . They were n't breathing when rescuers brought them up . The teen died at the hospital several hours later . Coroner investigator Joseph Cronin tells City News Service that the eight-year-old boy died Friday afternoon . Scroll down for video . Pulled from the water : A car plunged off a road into Los Angeles harbor on Thursday , and two children pulled from the submerged vehicle were hospitalized in grave condition . Both have now died . Rescue attempt : The two children pulled from the submerged vehicle by firefighters were hospitalized in grave condition , authorities said . Hero : Firefighter Miguel Meza ( left ) who dove into the water in San Pedro after a car carrying a family of four plunged into the water has been hailed a hero on the Facebook of City Councilman Joe Buscaino ( right ) The car left a parking lot at the Ports O ' Call entertainment area of San Pedro shortly after 6pm and ran off the road at Berth 73 of the Port of Los Angeles . The car traveled some distance before lurching into the harbor , where it landed upside down in about 30 feet of water just off of Berth 73 , Fire Department spokesman Brian Humphrey said . 'They looked like they were doing about 30 mph and turned right off the wharf , right into the water , ' said fisherman Ray Prince , 33 . 'The car just sunk . ' The man came up first and swam quickly to a ladder out of the water , Prince said . 'The poor lady was screaming hysterically . Just screaming . I thought she was going to drown , ' he said . The adults were described as being in fair condition but 'clearly emotionally distraught ' . Firefighter Miguel Meza , who dove into the water , has been hailed a hero on the Facebook page of Los Angeles City Councilman Joe Buscaino . 'Firefighter Miguel Meza jumped into the water at Berth 73 tonight in San Pedro after a car with a family of four drove into the water . This man is a true hero in the City of Angels and I am so proud of him ! , he said . Sucessful search : Divers emerge from the water as debris believed to be from the car floats to the surface where a car went off the berth and into the water . Divers working in murky water searched the car and even opened the trunk , but they found no one else in it , Humphrey said . The cause of the accident was under investigation . 'We do n't know at this time whether it was an accident or an intentional event , ' Humphrey said . Nearly 100 firefighters , divers and helicopter and boat crews went to the scene , Humphrey said . ABC reports that the event that led up the incident remain unknown . Witnesses told police that they heard screeching tires before the car made the plunge . Two dead : One of the children who fell into the LA Harbor died Thursday , while a second was confirmed as dead on Friday .
Car plunged off a road into Los Angeles harbor on Thursday . The parents swam to the surface but the Two boys were trapped . Both died were pronounced dead in hospital . The adults are in a fair condition . Police are investigating whether the crash was intentional . The victims have not been identified . Firefighter Miguel Meza who dove into the water has been hailed a hero .