A medical flight carrying six people has gone missing off the coast of Massachusetts in the United States.

The aircraft, which departed from Bermuda, vanished after suddenly losing both radio and radar contact mid-air, following a rapid descent from approximately 24,000 feet and an emergency distress signal from the pilot.

According to the BBC, the medical flight, bound for Boston in the U.S. state of Massachusetts, went missing in the early hours of Saturday (October 3) local time.

U.S. authorities are currently conducting extensive air and sea search operations to locate the six people on board.

The U.S. Federal Aviation Administration (FAA) told the BBC that communication with the Gulfstream G-100 aircraft was abruptly lost. Search and rescue operations were launched shortly after 1:00 AM local time.

The U.S. Coast Guard Northeast District stated that search efforts are concentrated off the coast of Nantucket Island, Massachusetts, utilizing both aviation and maritime assets.

According to FlightAware data, the aircraft took off from L.F. Wade International Airport in Bermuda at 11:40 PM local time and was scheduled to land at Boston's Logan International Airport at 1:30 AM local time.

Based on the tail number released by the Coast Guard, the plane belongs to Latitude Air Ambulance, an organization that operates international medical flights to repatriate patients for continued treatment in their home countries.

Clarence Togeretzy, Director of Flight Operations for Latitude, told CBC News that the aircraft was manned by two pilots and two medical crew members, all of whom are Canadian citizens.

Togeretzy noted that the crew had traveled to Bermuda to pick up a patient and an accompanying family member, neither of whom are Canadian citizens.

Flight tracker data from FlightAware shows that prior to losing contact, the aircraft experienced a sudden and steep descent, dropping from roughly 7,300 meters (24,000 feet) down to about 3,300 meters (11,000 feet).

According to the Boston Globe, based on air traffic audio logs from LiveATC.net, communication difficulties arose between the pilot and air traffic control.

An air traffic controller was heard asking the pilot, "Are you proceeding without instructions? Is that what you said? Are you declaring an emergency, or are you not?"

The pilot's response was inaudible, prompting the controller to reply, "Your signal is very weak, so I didn't catch your response regarding whether you have declared an emergency."

The air traffic controller subsequently confirmed that the pilot had indeed declared an emergency.

Shortly after 1:00 AM local time, fire dispatchers alerted emergency rescue teams to stand by for the aircraft, noting that the plane was experiencing "electrical issues."

The dispatcher later confirmed, "The aircraft has lost both radio and radar contact."