If you're talking about Andy Lopez, that was just in November of last year. He was 13 when he was shot-and-killed while carrying a BB gun. In Chicago, in 2011, Jimmell Cannon was killed the same way. He was also 13.
They are far from alone. Here's an article about 17-shootings that involved fake guns, and this only touches on the number of incidents actually occur. In 2011, when a teen was killed the same way in Los Angeles, Sen. Kevin de León (D - Los Angeles) tried to pass a bill that would have required BB guns be painted bright colors. It failed. As a result of the 2013 shooting, the issue was revisited.
De León eventually won passage of a measure that exempted Los Angeles County from a state law that prohibits local governments from regulating guns. A proposed Los Angeles city ordinance that would permit the sale of BB guns and other imitation firearms only if they are brightly colored is now being drafted by the city attorney's office and may be introduced later this year.
However, I fail to see how this will help if open carry enthusiasts are brightly decorating their guns to look like toys. Some manufacturers even make real guns that look like toys and are designed to be sold as a child's "first" weapon. How are police supposed to know the difference?