Rescuers are still searching for three people missing after a boat sank in San Francisco Bay near Alcatraz Island. One person had been rescued but later died, and 16 others were saved after the vessel got into trouble Tuesday afternoon. The city's fire department said its boats were still searching as of sunrise Wednesday morning. The search has involved divers, helicopters, and vessels. The cause of the sinking remains unclear. Videos showed the boat largely submerged with objects floating nearby as rescuers arrived. The boat was about 600 yards from Alcatraz when the emergency call came in.