Smoke was detected in multiple places on EgyptAir flight 804

The Imam of al Thawrah Mosque, Samir Abdel Bary, gives condolences to Tarek Abu Laban,
center, who lost four relatives, all victims of Thursday's EgyptAir plane crash, following prayers for the dead, at al Thawrah Mosque, in Cairo, Egypt, Friday, May 20, 2016. The Airbus A320 plane was flying from Paris to Cairo with 66 passengers and crew when it disappeared early Thursday over the Mediterranean Sea.

Agency spokesman Sebastien Barthe told The Associated Press that the plane's automatic detection system sent messages indicating smoke a few minutes before the plane disappeared from radar while flying over the east Mediterranean early on Thursday morning.

The messages, he explained, "generally mean the start of a fire," but he added: "We are drawing no conclusions from this. Everything else is pure conjecture." The industry publication Aviation Herald also reported that sensors detected smoke in the plane's lavatory, suggesting a fire onboard.

Looking for clues to whether terrorists may have brought down the Airbus A320, investigators have been poring over the passenger list and questioned ground crew members at Charles de Gaulle Airport in Paris, from which the plane took off.

The Airbus A320 had been cruising normally in clear skies on a nighttime flight to Cairo early Thursday when it suddenly lurched left, then right, spun all the way around and plummeted 38,000 feet (11,582.4 meters) into the sea, never issuing a distress signal.