(CNN)EgyptAir Flight 804 vanished from radar Thursday morning on its way from Paris to Cairo. Questions abound, including the location of the vital, so-called black boxes.
EgyptAir Flight 804: What we know
Here's what we know so far:
On Saturday, the Egyptian armed forces displayed debris and belongings from Flight 804 found a day earlier in the Mediterranean Sea.
Passengers' belongings and parts of the aircraft were discovered 290 kilometers (180 miles) north of the Egyptian coastal city of Alexandria, according to the armed forces. Later, a Greek military spokeswoman confirmed Egyptian searchers said they'd also found a body part and a portion of an airline seat.
Egyptian Foreign Minister Sameh Shoukry told CNN the searchers will press on but it isn't clear how long it will take to recover the cockpit voice and flight data recorders -- also called black boxes -- to find out what happened on the flight.
The United States, France, Britain, Russia and others are eager to cooperate in the search, Shoukry said.
"We do not, I think, have the technical abilities to operate in such deep waters, whereas many of our partners might have this facility," he said.
The European Space Agency said one of its satellites had spotted an oil slick in the general area where the plane disappeared. The slick could be entirely unrelated, the agency said.
Greek air traffic controllers talked to the pilot when the plane was near the Greek island of Kea. Everything seemed fine until the plane, which was over the eastern Mediterranean Sea, approached Egyptian airspace.
About 2:27 a.m., Greek air traffic control tried to reach the pilots to hand off control to Egypt. But the pilots did not respond; officials don't know why.
Immediately after entering Egyptian airspace, the plane swerved 90 degrees to the left and then turned 360 degrees to the right.
It descended from 37,000 feet to 10,000 feet "when we lost the signal," Greek Defense Minister Panos Kammenos told reporters.
The plane vanished while cruising -- the safest part of the journey, CNN aviation correspondent Richard Quest said.
Smoke alerts occurred on the plane in the minutes before it crashed, according to flight data CNN obtained Friday from an Egyptian source.
The data was filed through the Aircraft Communications Addressing and Reporting System, or ACARS, a data link for sending messages between planes and ground facilities. A screen grab of data has time stamps that match the approximate time the aircraft went missing early Thursday.
The ACARS screen grab provided information about smoke and heat on a window near the co-pilot and in the lavatory, which was behind the cockpit, CNN aviation analyst David Soucie said.
"If there's fire on board the aircraft, in this area which the ACARS indicates, then something was close to the cockpit," Soucie said. "It could have been either something mechanical that had failed, a short circuit, or it could have been an incendiary device of some kind as well."
ACARS does not provide a cause of the crash, but Soucie said it was significant that the data was sent over a period of one to two minutes.
There were indications of problems with a heated window in the cockpit, a sliding window in the cockpit, smoke in the lavatory, smoke in the avionics compartment below the cockpit, a fixed window, the auto pilot and the flight control system.
The Airbus A320 made stops in Eritrea and Tunisia earlier Wednesday, data from flight-tracking websites show.
Flight 804 left Charles de Gaulle Airport in Paris at 11:09 p.m. Wednesday and was supposed to land in Cairo at 3:15 a.m. Thursday. (Paris and Cairo share the same time zone. All times listed below are for Paris/Cairo.)
The 66 people on board included 30 Egyptians and 15 French, EgyptAir said.
Others were from Britain, Belgium, Iraq, Kuwait, Saudi Arabia, Sudan, Chad, Portugal, Algeria and Canada. Australia said the British passenger was also an Australian citizen.
Three children were among those on board, including two infants, EgyptAir Vice Chairman Ahmed Adel said.
Egyptian Civil Aviation Minister Sharif Fathy said there were no known security issues with passengers on the plane but said further checks are underway.
The airline said it will release the passenger manifest after next of kin are contacted.
EgyptAir officials met with families Saturday to explain the process of identifying bodies, saying the recovery and identification process will be lengthy because of the retrieval of body parts and time for DNA testing.
Families were asked to provide information helping investigators to identify body parts.
The captain -- identified to CNN by an official close to the investigation and a security source as Mohamed Said Shoukair -- had 6,275 flying hours, including 2,101 on the A320.The first officer, whom the two sources said is named Mohamed Mamdouh Ahmed Assem, had 2,766 flying hours.
The Airbus A320 was part of EgyptAir's service since November 2003 with about 48,000 flight hours.
Routine maintenance checks were done Wednesday in Cairo before it left for Paris, an airline official said.
The plane's engines were made by U.S. company Pratt & Whitney, according to an American official. The National Transportation Safety Board is in contact with Pratt & Whitney, and ready to assist in the investigation if asked by Egyptian authorities.
The weather was clear and calm when the plane crossed over the Mediterranean, CNN meteorologist Pedram Javaheri said.
Egypt has formed an investigative committee, and France has sent officials to help with the inquiry.
The cause is more likely to be terrorism than a technical issue, said Fathy, Egypt's civil aviation minister.
"I don't want to go to speculation. I don't want to go to assumptions like others," Fathy said. "But if you analyze this situation properly, the possibility of having a different action aboard, of having a terror attack, is higher than having a technical problem."
The early hypothesis of U.S. government officials is terrorism, with the initial suspicion that a bomb took down the plane, officials told CNN. They cautioned their suspicion was not based on any concrete evidence but on the circumstances.
French Foreign Minister Jean-Marc Ayrault told passengers' family members Saturday that 'no theory" has been ruled out.
The United States has found no indications of an explosion, but agencies are reviewing systems and satellites that monitor Mediterranean activity for signs of a possible blast at the time of the plane's disappearance, defense officials said.
"I'm not aware of any sensors that the U.S. military has or deploys -- air or maritime -- that picked anything up on this," State Department spokesman John Kirby told reporters.