Story highlights No one was hurt and no property was damaged, the Navy says

The drones cost $176 million apiece

Navy drone crashes near Salisbury, Maryland

The RQ-4A Global Hawk was on a training mission, the Navy says

A U.S. Navy drone crashed Monday in a marsh near Salisbury, Maryland.

The RQ-4A Global Hawk drone crashed during a routine training flight from Naval Air Station Patuxent River, according to Jamie Cosgrove, a spokeswoman for the Unmanned Aviation and Strike Weapons Program at the base.

There were no injuries to civilians and no property damage, said the Navy, which said it is investigating the cause.

Video from CNN affiliate WBOC showed smoke rising from brush fires in the unpopulated area.

The drone crashed into a tributary of the Nanticoke River, a U.S. Coast Guard official said. The crash site has been blocked to recreational boat traffic while the agency investigates, the Coast Guard official said.

As soon as Navy personnel lost contact with the unmanned vehicle, a piloted aircraft was dispatched to Maryland's Eastern Shore, where it came upon the wreckage and determined that it was unlikely anyone on the ground had been hurt, Navy officials told CNN.

The crash occurred at about 12:11 p.m., near Bloodworth Island in Dorchester County, the Navy said.

The aircraft is one of five aircraft acquired from the Air Force Global Hawk program. The BAMS-D program has been developing tactics and doctrine for the employment of high-altitude unmanned patrol aircraft since November 2006.

The drone can fly for 30 hours without refueling at altitudes as high as 11 miles. It is typically used for reconnaissance. Of the five drones based at southern Maryland's Naval Air Station Patuxent River, four are in routine training and one is deployed with the U.S. Navy Fifth Fleet, the officials said.

The basic RQ-4A Global Hawk UAV, manufactured for the U.S. Air Force by Northrop-Grumman, is the largest and most advanced drone in the U.S. military, according to the Navy. It is 44 feet long, has a 116-foot wingspan and weighs 25,600 lbs.

The vehicles cost $176 million apiece, the Government Accountability Office reported in 2010.

Crashes are highly unusual, Navy officials said.