NEW YORK. Police in New York City have launched an investigation after people were seen emerging from manholes (covers for drains and underground utility systems) in recent weeks.This investigation was initiated after many videos went viral on social media. Those videos show people emerging from the underground drainage system at various locations during the night.In a statement on Monday, the New York City Police Department said, ‘NYPD sent officers from its highly trained Emergency Service Unit into the sewer system to ensure there was no threat to public safety. They searched to see if any harmful or suspicious items were...