Undated file photo courtesy of the U.S. Navy shows a RQ-4 Global Hawk unmanned aerial vehicle conducting tests over Naval Air Station Patuxent River, Maryland. An unarmed U.S. Navy drone aircraft crashed on Monday during a test flight in Maryland, plummeting into a marsh area around the Chesapeake Bay without injuring anyone or causing property damage, the Navy said. The cause of the crash of the unmanned spy plane was under investigation, a Navy spokesman said. The incident took place near Bloodsworth Island, about 70 miles southeast of Washington DC, at around noon. REUTERS/U.S. Navy/Erik Hildebrandt/Northrop Grumman/Handout (UNITED STATES – Tags: MILITARY) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS