A U.S. Air Force F-35B fighter jet crashed after it collided with an aerial refuelling tanker on Tuesday, a U.S. marines unit said

The pilot of the F-35B jet ejected and was being treated, while the crew of the KC-130J refuelling aircraft had landed safely, the 3rd Marine Aircraft Wing said.

The crash occurred over Imperial County, California, ABC News reported.

"At approximately 1600 it was reported that an F-35B made contact with a KC-130J during an air-to-air refuelling evolution, resulting in the crash of the F-35B," the 3rd Marine Aircraft Wing said in a tweet.

The cause of the crash was under investigation, the marines said.

The refuelling plane had returned to Thermal Airport and all crew members were safe, it added.

The marines unit did not immediately respond to a request for comment.