Anime question for anime fans

ok, so perhaps this is a completely ridiculous question as it is very vague, but i'll attempt to ask it anyway. i remember when i was younger watching a bunch of anime on the sci-fi channel sometime after midnight. most specifically i recall a series/movie (i'm unsure which) set in the future in which a small group of people were lead by a girl with a shotgun and possibly a brown trenchcoat. i also think that i remember a small boy in the group of maybe 4? so that's it. thats absolutely all i can remember aside from the fact that i enjoyed it. i did a little searching recently and was unable to find any other information. again i realize that the information i provided may be in several anime movies/series but any feedback would be greatly appreciated. I'm fairly confident that i will know it as soon as i see it, so please make any suggestions you can think of. Thanks again guys.