A Boeing 737 cargo aircraft with two people on board made an emergency landing in the ocean off the coast of Honolulu, Hawaii, early on Friday, the U.S. aviation safety regulator said.

"The pilots had reported engine trouble and were attempting to return to Honolulu when they were forced to land the aircraft in the water," the U.S. Federal Aviation Administration (FAA) said in a statement.

According to preliminary information, the U.S. Coast Guard rescued both crew members.

The plane was operated by Rhodes Express.

CNBC earlier reported that a Boeing 737 had come down in the water.

Boeing was not immediately available for comment.

(With input from Reuters)