(Arlington, VA) — Several streets remain closed in the Arlington neighborhood where a house exploded last night. Video of the violent blast that leveled a brick home about a half-mile west of the Ballston-MU Metro station has gone viral. Federal investigators are working with local officials to determine the cause. Police were called to the home Monday afternoon after the man who lived there fired off a flare gun about three dozen times. Hours later, officers heard rounds from a firearm being discharged inside the house just as they were preparing to execute a search warrant and the explosion occurred shortly thereafter. Authorities still don’t know what happened to the man, who neighbors describe as a little bizarre.