WASHINGTON (DC News Now) -- The Metropolitan Police Department (MPD) said an investigation is underway after a 5-year-old boy died in Northwest. MPD said that at about 9:45 a.m. on Sunday, officers were called to the 4500 block of Connecticut Ave. At this location, officers began conducting a child death investigation. Police arrest man in connection to Southwest DC assault Police have not released the cause of the boy's death, and it is still under investigation, according to MPD. This is a developing story.