A small cargo plane crashed near Puerto Rico's northern coast, killing the two U.S. citizens who were aboard, officials said Tuesday.

Investigators had not yet identified the pilot and the passenger, Emergency Management Agency spokesman Carlos Acevedo said.

The plane originally flew from Florida to in the Dominican Republic either on Sunday or Monday, Acevedo said. It departed late Monday from the latter Caribbean country and was headed to Puerto Rico's main international airport when it crashed, said another agency spokesman, Jose Cruz.

Acevedo said the plane was carrying cargo that included mail, food and beverages.

The aircraft was operated by IBC Airways, based in Ft. Lauderdale, Florida. Officials with IBC Airways did not return a message seeking comment.

The plane crashed on a small mountain in the north coastal town of Arecibo, and officials with the U.S. Federal Aviation Administration were investigating whether the pilot had requested a change in altitude, Acevedo said.

An FAA statement said air traffic controllers lost contact with the flight when it was about 25 miles (40 kilometers) west of the capital of San Juan. The agency identified the aircraft as a Fairchild SA-227-AC cargo plane but released no further details. The plane was registered and its certificate issue date was valid through 2017.