Investigators Say Smoke Detected in EgyptAir Plane Before Crash

French investigators announced Saturday that smoke was detected in multiple places on the ill-fated EgyptAir plane before it plummeted into the Mediterranean Sea.

The Aviation Herald initially reported that sensors detected smoke in a lavatory, suggesting a fire on board the aircraft before it went down.

David Learmount, a noted aviation expert, told Fox News Friday that the data received from some satellites indicates that a fire could've started in the avionics compartment of the plane which knocked out computers and control mechanisms on the flight. He said that would've caused the plane to crash.

French officials didn't say what could have caused parts of flight 804 to fill up with smoke. Spokesman Sebastien Barthe told the Associated Press the plane's automatic detection system sent messages indicating smoke a few minutes before it disappeared from radar.

He said the messages "general mean the start of a fire."

"We are drawing no conclusions from this. Everything else is pure conjecture," Barthe added.

According to The Wall Street Journal, sensors aboard the plane detected smoke in the lavatory on the aircraft's nose. The paper, citing someone familiar with the aircraft's data, reported the messages suggest there was damage to the right-side of the cockpit windows.

Officials who have reviewed the data told The Wall Street Journal that the broadcast information by itself is insufficient to determine whether the plane crashed because of a bomb or another cause. Rockwell Collins, a global aviation telecommunications provider, said late Friday it transmitted the messages over its networks to the carrier in real time.

Learmount said the possibility of terrorism couldn't be ruled out. He said there were a couple other scenarios that could have caused the plane to crash:

• A terrorist got into the avionics compartment and placed a device that triggered the fire and alarm.
• All of these sensors were picking up smoke and then disablement following a bomb going off.
• The fault in the avionics and the terror attack happened concurrently.

Earlier Friday, an EgyptAir official confirmed that wreckage of the missing plane was found, including body parts, luggage and passengers' seats. The announcement came hours after a Greece official also reported evidence being found.

"A short while ago we were briefed by the Egyptian authorities... on the discovery of a body part, a seat and baggage just south of where the aircraft signal was lost," Defense Minister Panos Kammenos told reporters in Athens, according to Reuters.

The Cairo-bound flight had left Charles de Gaulle Airport in Paris late Wednesday night with 66 on board, and disappeared from radar as it neared its destination.

A flotilla of international ships and boats were searching a wide swath of the sea Thursday and during the night for debris from the ill-fated Airbus 320. The mile-long oil slick was identified from satellite images from the European Space Agency, which cautioned that there was no guarantee the slick was from the missing aircraft. The agency said the slick was about 25 miles southeast of the plane's last known location, and passed the information to relevant authorities late Thursday.

The Egyptian presidency Friday expressed its "deep sadness and extreme regret" over the deaths of the passengers and crew members aboard the flight -- the first official recognition of the tragic crash. Egypt's military also confirmed for the first time Friday that plane debris and passengers' personal belongings were found in the Mediterranean Sea.

Egyptian army spokesman Brig. Gen. Mohammed Samir wrote on his Facebook page that Egyptian jets and naval vessels participating in the search for the missing plane had found "personal belongings of the passengers and parts of the plane debris."

Egyptian airport officials said Friday that three French and three British investigators and an AirBus technical expert had arrived in Cairo to join the investigation.

No terror groups had taken credit for the disaster as of Friday morning, and authorities were going through the passenger manifest, crew members' backgrounds and airport staff for possible links to terror. Authorities said the plane swerved and spun wildly before plummeting into the sea. The Egyptian military said that no distress call was received from the pilot.

In Paris, French authorities scoured Charles de Gaulle Airport, the country's main hub, for any sign of a security breach prior to the flight's departure. Reuters reported that investigators were interviewing officers who were on duty at the airport Wednesday night to determine whether they heard or saw anything suspicious.

"We are in the early stages here," a police source told Reuters about the investigation.

The Wall Street Journal reported earlier Friday that French investigators were poring over surveillance footage from the airport, as well as performing background checks of those on board the plane and anyone who may have had ground access to the aircraft.

Flight 804 was carrying 56 passengers, including one child and two babies, three security staff and seven crew members, officials said. Egypt's aviation minister, Sharif Fathy, described those on board as including 15 French passengers, 30 Egyptians, one Briton, two Iraqis, one Kuwaiti, one Saudi, one Sudanese, one Chadian, one Portuguese, one Algerian and one Canadian.

Families of the victims spent the night in a hotel in the Egyptian capital, Cairo, while they awaited the news of their loved ones. Egyptian officials said some arrived from Paris late Thursday, among them eight relatives of the 15 French passengers on board the missing jet.

In Egypt, home to 30 of the victims, grieving families and friends wondered if their loved ones would ever be recovered. Many gathered in mosques for Salat al-Ghaib, or "prayers for the absent," held for the dead whose bodies have not been found.

"This is what is ripping our hearts apart, when we think about it. When someone you love so much dies, at least you have a body to bury. But we have no body until now," said Sherif al-Metanawi, a childhood friend of the pilot, Mohammed Shoukair.

Later Friday, the relatives of those killed held prayers for the dead at Sultan Hussein mosque in Cairo. Some of them cried as they prayed.

Among those killed were Salah Abu Laban, his wife Sahar Qouidar, their son Ghassan Abu Laban and daughter-in-law Reem al-Sebaei

The relative, Abdel-Rahman al-Nasry, told The Associated Press, "I ask God for forgiveness. This is very hard for the family."

Magdi Badr, a family friend, said, "we pray for the victims."

In the U.S., Los Angeles International Airport announced Thursday that it was stepping up security in the wake of the EgyptAir disappearance. A statement from airport authorities said they were eliminating or restricting airport worker access to 150 doors in the terminals.

The statement also said additional airport police officers had been assigned to monitor employee access points and conduct random screenings.

Fox News' Greg Palkot and The Associated Press contributed to this report.