A Egyptair passenger plane carrying 66 people that went missing Thursday over the Mediterranean while en route from Paris to Cairo crashed, French President Francois Hollande said.
Hollande said he directed French resources - including planes and boats - to be offered to Greek and Egyptian authorities to help find the aircraft and gather possible debris that could help "know the truth."
Until that point, Hollande warned against jumping to conclusions, saying that nothing could be ruled out at this point - including an accident or possible terrorist motive.
Egyptair Flight MS804 disappeared from radar over the Mediterranean Sea at 2:30 am local time (0030 GMT), some 45 minutes before it was expected at Cairo airport.
"Search operations are under way in the area where the aircraft has disappeared," an Egyptian army spokesman said in a statement, while Greece said it had sent two military aircraft and a ship to look for the Airbus A320 in the Mediterranean Sea.
Egyptian civil aviation officials, speaking on condition of anonymity, earlier said that Egyptair Flight MS804 had crashed into the Mediterranean. But Egyptian Civil Aviation Minister Sherif Fathy denied the plane had crashed saying that it could not be confirmed.
He also retracted an earlier statement by Egyptair that the Egyptian military search teams received a distress call from the emergency mechanisms of the plane almost two hours after its departure from Paris.
The jet carrying 56 passengers, seven crew members and three security officers took off from Charles de Gaulle Airport in the French capital late Wednesday.
All evidence seems to indicate that the plane crashed, said Greek Defence Minister Panos Kammenos on TV Thursday.
The plane was flying at 37,000 feet before it started making erratic moves, he said.
"At this time, the plane was 10 to 15 nautical miles in the Egyptian airspace," he said. "It then turned 90 degrees left, followed by another turn 360 degrees to the right before falling to 15,000 feet. Its radar image disappeared at 10,000 feet," the minister said.
The passengers included 30 Egyptians, 15 French nationals, two Iraqis and one each from Britain, Belgium, Kuwait, Saudi Arabia, Sudan, Chad, Portugal, Algeria and Canada, according to the airline. Three children were on board, the airline said.
The Paris prosecutor's office opened an investigation into what it called the plane's disappearance.
The airline named the pilot as Mohammed Said Ali Shaqir and said he had over 6,000 hours of flights logged, more than 2000 of them on Airbus A320s. The co-pilot had 2,766 flight hours logged, the company said.
The plane was delivered to the operator in 2003, its manufacturer Airbus said, adding that it had accumulated some 48,000 flight hours.
The Toulouse-based aircraft manufacturer added it had no further details on the flight but says it is ready to provide technical assistance to investigators.
Hollande and his Egyptian counterpart Abdel-Fattah al-Sissi agreed to cooperate fully.
Families of the people on board are being received at a hotel near Paris Charles de Gaulle Airport, French Foreign Minister Jean-Marc Ayrault said. An emergency line was also set up at the French embassy in Cairo, and two hotlines were opened in France by the airport and the Foreign Ministry.
At Cairo airport, families who had been waiting to meet passengers of the plane were brought to a private room and were being attended to by medical staff, officials said.
Thursday's crash comes in the wake of other recent incidents involving Egyptian aviation.
In March, a man used a fake explosive belt made of mobile phone covers and cables to force an Egyptair flight to land in Cyprus.
In October, a Russian passenger jet broke up in mid-air shortly after take-off from the resort of Sharm el-Sheikh in Egypt's Sinai Peninsula, killing all 224 people on board.
Russian authorities said that the incident was caused by a bomb. The Islamic State extremist group, which operates in Sinai, claimed responsibility and published a photograph of a soft drink can which it said had been filled with explosives and smuggled onto the flight.