CAIRO/ATHENS: An EgyptAir jet carrying 66 passengers and crew from Paris to Cairo disappeared from radar in what Egypt said could have been a terrorist attack.

Egypt’s aviation minister said a terrorist attack was more likely than a technical failure. A Greek air safety official said the debris found so far in the Mediterranean Sea does not belong to an aircraft. Greece had deployed aircraft and a frigate to search for the missing Airbus. Egypt said it would lead the investigation and France would participate.

Greek Defense Minister Panos Kammenos said the jet swerved 90 degrees to the left, spun through 360 degrees to the right and plunged from 37,000 feet to 15,000 before vanishing from Greek radar screens.

Greece’s civil aviation chief said calls from Greek air traffic controllers to flight MS804 went unanswered just before it left Greek airspace, and it disappeared from radar screens soon.

The jet was carrying 56 passengers — with one child and two infants among them — and 10 crew. They included 30 Egyptian and 15 French nationals, along with citizens of 10 other countries.

Asked if he could rule out terrorist involvement, Egypt’s Premier Ismail said: “We cannot exclude anything at this time or confirm anything. All the search operations must be concluded so we can know the cause.”

US Democratic presidential frontrunner Hillary Clinton said she believes the crash was likely terror-related. “It does appear that it was an act of terrorism,” Clinton told CNN. “Exactly how, of course, the investigation will have to determine. But it once again shines a very bright light on the threats that we face from organized terror groups.”

Aviation experts agreed there is little chance that a mechanical fault was responsible. “A major technical fault — the explosion of an engine, for instance — seems improbable,” said aeronautics expert Gerard Feldzer.

“It’s a modern plane, the incident happened in mid-flight in extremely stable conditions. The quality of the maintenance and the quality of the plane are not in question in this incident,” Jean-Paul Troadec, former director of France’s aviation Bureau of Investigation and Analysis, said.

“We cannot exclude the possibility that it was shot down by another aircraft by mistake, but it is likely we would already know,” said Feldzer.

The region around northern Egypt, including the coastlines of Israel and Gaza, is “one of the most monitored regions in the world, including by satellite. It would be very difficult to hide this kind of information.”

That leaves a terrorist attack as the most likely possibility, the experts said, not least because it appears that no distress signal was sent from the jet.