Or the perp could go straight at the light into the Lake Barcroft community and you can get to Columbia Pike, route 50, the beltway, route 395, route 7 or a vast area of older homes to hide near in 15 minutes at that time of the night. It took the police 15 minutes to set up roadblocks.
If that is true, the roadblocks are useless and are being done to put on a show for the public. In 15 minutes the sniper will be in a 10X larger area outside the bounds of where the cops are looking. If true, that's just astoundingly bad.