A moose apparently annoyed by being shot with a tranquilizer dart charged the rear rotor of a hovering helicopter, colliding with it and eventually bringing it down to the ground. The pilot and a wildlife biologist aboard the helicopter were not injured in the incident but the moose had to be euthanized.

As a part of his study on moose, biologist Kevin White shot the animal with a tranquilizer dart and followed it while the pilot maneuvered the helicopter to keep the animal from slipping into a tight space or collapsing in water and drowning, Doug Larsen, regional supervisor for the Division of Wildlife Conservation told the Anchorage Daily news.

"I have never personally seen or heard of an injury of this type, caused to an animal by an aircraft," he said. "It just had to be one of those quirky circumstances. Even dealing with bears and goats and moose and wolves, this is pretty unusual and truly a very unique situation."

According to Larson, the moose was expected to move in the open spaces, but it instead ran towards the helicopter without giving the pilot a chance to get out of its way.

The animal was badly injured in the incident and had to be euthanized at the scene.

The incident happened near Gustavu, about 50 miles northwest of Juneau in southeast Alaska.