Two U.S. intelligence officials told NBC News there was "nothing finite, nothing specific" in chatter about a coming attack on aviation. There is nothing out there yet to confirm "foul play," according to the officials.
The Greek army deployed two aircraft, a frigate and two helicopters to the search and rescue operation 130 nautical miles south-southeast of the Greek island of Karpathos. The announcement was in addition to shipping data purportedly showing other marine traffic changing course to help the operation.
The U.S. State Department said that while it is still working on this case, it currently does not see any indications that American citizens were on EgyptAir MS804.
Reports of what could have happened to the plane in the moments before its disappearance started to emerge throughout the morning. Greek Defense Minister Panos Kammenos told a news conference that the plane had made "sudden swerves" and then plunged before dropping off radar.
Meanwhile, Egypt's civil aviation minister, Sharif Fathy, told a news conference that "no hypothesis had been ruled out" and that it could be a "terrorist act or a technical act." He refused to say the plane had "crashed," however, and said he would use the term "missing plane" until debris was found.
Greece has banned flights from an area stretching 40 miles around the last point of signal from the flight.
EgyptAir is updating its Twitter account regularly and said Egyptian Prime Minister Sherif Ismail had arrived at the airline's crisis center after cutting short a visit to Jeddah, Saudi Arabia.
The airline urged restraint from the media in the reporting of the incident amid conflicting accounts about distress signals from the missing plane.
News of the incident emerged in the early hours of Thursday. In an Arabic-language Facebook post just before 5 a.m. local time, EgyptAir cited an "official source" as saying the flight, which took off from Paris' Charles de Gaulle Airport at 11.09 p.m. Paris time, had "disappeared from radar in the early hours of (the) day."
In a series of subsequent tweets and statements, EgyptAir said the plane — an Airbus A320 — was carrying 56 passengers, including one child and two infants, as well as three of the airline's security personnel and seven crew members, taking the total number of people on board to 66.