That's not quite correct. I imagine that you are thinking of this FBI report that indicates that you are more likely to be struck by lightning than killed in a mass shooting. Mass shooting are a tiny fraction of gun violence in the US. There are around 50 lightning strikes a year in the US and about 80,000 shootings. Granted, about 80% of the shooting are gang-related. Even considering only 20% of the shootings (16,000), you are still 320 times more likely to be shot than hit by lightning.