The link to is an article in German. Here's the gist based on Google's translation (slightly corrected):The Brunswick Carnival parade has to be canceled because of a "concrete danger of an attack with Islamist background". The police are asking all the visitors, "not to go near the parade route or not even to make the trip to Brunswick."
This was announced by the Brunswick police. The police's statement said, "From reliable sources state security had become aware of a specific threat of an attack with Islamist background."