In one of the first large military drone crashes in Hawaii, an Army RQ-7B Shadow aircraft out of Wheeler Army Airfield went down in the mountains behind the base Wednesday afternoon, causing a brush fire, the 25th Infantry Division said.

No personnel were injured and no otheraircraft were in the area at the time of the crash, the Army reported.

Sgt. 1st Class Chuck Burden, a division spokesman, said in a statement: “We can confirm there was an unmanned aerial system, or drone, operated by the 25th infantry Division, that was lost during a routine training flight at approximately 3:30 p.m. Efforts are currently under way to survey the crash site to determine what, if any, additional impact to the area took place as a result. At this time, the cause of the loss is unknown. It will be determined later following an official investigation.”

Two Army UH-60 Black Hawks were dispatched to check out the crash site.

The Honolulu Fire Department responded to the brush fire. HFD had five units including Air 2, its helicopter, responding with nine personnel.

The Honolulu Police Department’s helicopter was also expected to assist with its helicopter to make water drops, HFD Capt. Scot Seguirant said. He described the location as the mountains above Kunia.

The Army’s Wildland Fire Department and Federal Fire Department also responded.

The crashed drone was a newer RQ-7Bv2 Shadow, which has a wingspan of 20 feet, weighs more than 440 pounds, and costs around $1.5 million. An older version of the Shadow had a 14-foot wingspan. Both types are propeller driven.

No armament was attached to the aircraft, the Army said.

Shadows provide Army units with near-real-time reconnaissance, surveillance and targeting, and “teaming ability” with AH-64D/E Apache attack helicopters, according to the Army.

Video from the Shadow is relayed to the cockpit of the Apache. Apache crew members also can remotely control the drone’s flight, electro-optical sensors and laser designator to fire Hellfire missiles from the helicopter. The drones can fly for nine hours.

No Apaches were flying with the Shadow at the time of the crash. The Hawaii Army National Guard also operates Shadows which have flown out of Wheeler.

Over the past decade, drones have been increasingly added to the military inventory in Hawaii as their surveillance capabilities increased. In late 2018, Marine Corps Base Hawaii began receiving 20 RQ-21A Blackjacks with a 16-foot wingspan that weigh about 135 pounds apiece.

In 2017 an Army Shadow being used in training in southern Arizona flew off course and was found stuck in a tree nine days later and 600 miles away in Colorado.