It's all over the news and 8ch's own twitter. You don't have to take my word for it. You can just look it up.
And, no, the US does not have laws against hate speech. It's actually protected under the constitution. What IS illegal though is either running or hosting a terror cell which, given the repeated incidents over such a short timespan, certain boards on 8ch can be interpreted as. Even still, it wasn't the govt that shut it down. It was Cloudflare. Free speech is not protected if you use someone else's "house" as your platform.