How long has the behavior been happening? Is it just one bird or several? Typically if a bird is swooping down and attacking people, it is protecting a nest. If that is the case, if you can find the nest, you can let people know not to go near it. That should solve the problem. Red-winged blackbirds are protected by federal and state laws. You aren't likely to get a removal permit if the bird is just being a temporary nuisance. Children should be instructed to wave their arms in the air if the bird dives at them. If you don't think this is just a case of an over-protective father bird, please e-mail me at email@example.com.