The Colorado Air National Guard says an F-16 fighter jet landed safely after an unspecified emergency during a training flight over Colorado and Kansas.

The Guard says the pilot was unharmed but the plane jettisoned two empty external fuel tanks over an unpopulated part of Elbert County, Colo. The county is about 30 miles southeast of Denver.

Maj. Nicole David says officials are searching for the tanks. David says the tanks aren't dangerous but are important to the investigation.

David says the jet wasn't carrying weapons.

She said she didn't know the nature of the emergency.

The jet took off from Buckley Air Force Base outside Denver and landed at Peterson Air Force Base in Colorado Springs, about 60 miles south.