The United States Coast Guard suspended its search last night for an air ambulance carrying two Bermudians and four Canadians which crashed off Nantucket, Massachusetts, early on Saturday morning.

The coast guard’s Northeast District said a “future investigation into the cause of the incident will be co-ordinated by the appropriate investigative authorities”.

The coast guard had been searching for the air ambulance since Saturday — a Gulfstream G100 jet, registration C‑GRJP, travelling from Bermuda to Boston — focusing on a debris field confirmed to be from the aircraft off the coast of Nantucket, Massachusetts.

“Suspending a search is not an easy decision,” said Rear Admiral Matthew Lake, Commander of the Northeast District. “We express our deepest condolences to the families and loved ones affected by the tragedy, and our gratitude for our partner agencies who helped support search efforts.”

Wreckage was sighted at sea in the search for four Canadian crew along with a medical patient and companion, both from Bermuda.

The coast guard held a press conference at noon yesterday, after search crews last night located the debris field.

It was broadcast by Boston 25 News. Speakers were Rear Admiral Lake, joined by Captain John McTamney and Lieutenant-Commander Kastriot Kastrati, the search and rescue co-ordinator. No identities were given for those on board.

Air traffic controllers said the pilot of the craft had declared an emergency because of electrical issues. The plane was lost roughly 20 miles off Nantucket.

By the time the search was suspended, it had covered 4,445 square miles of sea over approximately 66 hours.

The decision to suspend the search suggested that efforts would be made to recover the plane and to end the rescue mission.

Mr Lake said earlier yesterday that the US Coast Guard was “in the process of working with Massachusetts authorities” to bring a craft into the search with sonar capabilities to scan the sea floor.

Craft from the New York National Guard’s Air Rescue Wing also assisted in the search.

The debris field off Nantucket was said to be “extensive”, with a depth of 80 to 90 feet.

Mr McTamney explained the level of debris made it “very difficult to get into the details of what’s there”.

He said the weather had been “favourable for searching”, adding: “We’ll continue to search and saturate the area until we’re at the point that, if there were any survivors remaining on the surface of the water, we would have found them.”

The rear admiral said: “I want you to know that my thoughts and those of every Coast Guard crew member are with the people on that aircraft, their families, their friends and their loved ones during this incredibly difficult time.”

Earlier, NBC News reported that two people from Bermuda, along with four Canadians, were missing after the plane disappeared from radar.

David Burt, the Premier, said that the Government has been in contact with the families of those on board and remains in contact with the overseas authorities carrying out the search.

He added: “My thoughts are with everyone on board and their families during this deeply worrying time.

“We are praying that all six people will be found safe, and we thank the search and rescue crews for their continuing efforts.”

Gilbert Darrell, of Bermuda Air Ambulance, said: “I will just say publicly how horrendous this is. Our thoughts are with the nurses, the pilots and with the local people involved.”

Mr Darrell said the loss of the aircraft was unprecedented in the island’s recent aviation history, but that details would emerge once the flight recorder was recovered.

A spokeswoman from Skyport said on Saturday: “Skyport can confirm that a Canadian-registered air ambulance departed LF Wade International Airport for Boston at approximately 12.41am on October 3 with six souls on board, including four crew members and two passengers.

“The US Federal Aviation Administration has advised that air traffic controllers subsequently lost contact with the aircraft off the coast of Nantucket Island, Massachusetts, and a search is under way.

“Skyport has no further information to provide at this time.”

The early investigation this weekend included crews from Air Station Cape Cod, a 47ft motor lifeboat crew from Station Brant Point and the USCGC William Sparling.

The aircraft had been expected to arrive at Boston Logan International Airport at 1.30am. The Federal Aviation Administration sent out an alert at 1.20am.

Massport, which operates the Boston airport, said in a statement: “Our thoughts are with those on board and their loved ones as the search continues.”

Flight tracking website Flightradar24.com said the missing aircraft was owned by Latitude Air Ambulance, based out of Hamilton Ontario, which is understood to have regularly operated flights from Bermuda.

Clarence Togeretz, the director of flight operations for Latitude Air Ambulance, told NBC News on Saturday: “We always get rather concerned when our crew doesn’t report to us in a timely manner, but I will say that again, optimistically and positively, that doesn’t mean that the worst has happened.”

He also told the news outlet that there was an emergency response plan in place “absolutely for anything that might occur to any of our missions”.

Mr Togeretz has confirmed to the Canadian Broadcasting Corporation that the crew of the flight, including two pilots and two medical staff, were Canadians who had flown to Bermuda to transport a patient and their relative, who are understood to be Bermudian.

Air traffic control audio obtained by NBC appeared to show controllers asking if the aircraft was “coming in blind” before requesting that another aircraft attempt contact.

The Associated Press reported that bad weather was ahead of the aircraft shortly before contact was lost.

AP quoted Mary Schiavo, former Inspector-General of the Transportation Department, who speculated that the plane may have lost its navigational instruments just as a storm moved across its path on radar.

She told the news service: “Something bad happened with this big drop, and they flew into this big storm. It’s a terrible place to have a loss of your instruments and be flying blind.”

Ms Schiavo told AP the circumstances could have made it “very easy to get disoriented and not know if you’re turning, climbing, descending”.

Nantucket Memorial Airport said in a statement on social media that the airport was informed the aircraft declared an emergency prior to the loss of contact.

However, the statement said details remained unconfirmed.

Flight data from FlightAware, meanwhile, suggested that the aircraft dropped rapidly in altitude from 24,000ft to 11,000ft shortly before communications halted.

Flightradar24 yesterday showed coast guard aircraft sweeping an extensive area immediately south of Nantucket.

Steven MacKinnon, the Federal Minister of Transportation in Canada, said in a social-media post: “My thoughts are with everyone on board, as well as their families, loved ones and colleagues during this incredibly difficult time.”