OAKLAND, Calif. (KGO) -- People hanging out on Tuesday at Oakland City Center got an "operatic" surprise. A flash mob chorus of 50 broke out into song during lunchtime.The group is from the Oakland-based nonprofit James Toland Vocal Arts," which helps develop and promote singers' careers.Organizers say the impromptu choral event took 10 months to plan. And from the looks of the pleased crowd, it was well worth it.JTVA will sponsor a vocal competition next month at Valley Center for the Performing Arts at Holy Names University in Oakland to give money to some up and coming singers.