AeroVironment Inc’s experimental Global Observer unmanned aircraft crashed during a flight test at Edwards Air Force Base early Friday morning.

What the Monrovia drone developer described as a “mishap” occurred at 2:30 a.m., about 18 hours into the ninth test flight of the high altitude, long-endurance craft. There were no reports of injury or damage to other property and an investigation is underway, the company said.

A joint U.S. government and AeroVironment Global Observer team was attempting to expand the flight envelope of the hybrid-electric vehicle, which had been operating at a higher altitude and for nearly twice the length of previous flights when the incident occurred, the company said.

“Flight testing an innovative new solution like Global Observer involves pushing the frontiers of technology and convention,” said Chief Executive Tim Conver in a statement. “Risk is a component of every flight test program, and the learning that results from a mishap enables us to improve system reliability and performance.”

The surveillance plane is designed to fly at 55,000 to 65,000 feet for up to seven days, according to Aviation Week. The trade publication also reported that the crash involved the single prototype that had been completed. A second is said to be nearly complete.

AeroVironment received a U.S. defense contract for developing and demonstrating the Global Observer in September 2007. Six U.S. agencies providing more than $140 million in funding for the program, most of which has been spent, the company said.

Analysts at KeyBanc Capital Markets downgraded shares from “buy” to “hold.” “Edwards Air Force base defines a mishap as a crash, and at this point all we know is that the Global Observer presumably crashed,” the analyst’s report said.

AeroVironment made the announcement at midday, and shares fell $4.16, or nearly 12 percent, to close at $30.82 on the Nasdaq.