Authorities are still looking into an explosion in northwest DC. The cause is not clear. Police are also looking into a incident that left three people injured. No suspect has been named. Forecasters say there will be showers today with colder windy weather expected later in the week. Meanwhile a proposed 250-foot arch near Arlington Cemetery is in a legal fight. Kennedy relatives say the structure would cast shadows on gravesites and disrespect their ancestors. The lawsuit names the arch project, which was originally proposed by former President Donald Trump, as the defendant.