ELMENDORF AIR FORCE BASE, ALASKA  — A large military aircraft crashed at Elmendorf Air Force base in Anchorage on early Wednesday evening, officials said, but there was no immediate word on casualties.

The Boeing C-17 Globemaster III aircraft went down at the end of the runway around 6.14 p.m. local time, and large plumes of black smoke was seen rising from the scene, according to the Alaska National Guard.

Bob Hall, a spokesman for the base, said the Air Force cargo aircraft was assigned to the 3rd Wing at Elmendorf Air Force Base. “At the time of the accident, it was on a local training mission,” he said.

Hall said four crew members were on board the aircraft. “Their condition is unknown at this time,” Hall said. “First responders are on scene.”

A spokesman for the Anchorage Fire Department said they were not involved in the emergency response.