Russian airline Metrojet on Monday rejected the possibility that a technical fault caused its aircraft to crash in Egypt on Saturday, which killed all 224 people on board.

An official from the airline blamed an “external factor” for the crash, saying the cause “could only have been a mechanical impact on the plane” in the air, reported The Guardian. He added that the plane dropped 186mph (around 300kph) in speed and about 5,000 feet in altitude a minute before it crashed into Egypt’s Sinai peninsula.

Earlier on Monday, the bodies of 140 victims of the crash arrived in St Petersburg aboard a Russian government aircraft, reported Reuters. Russia’s emergency ministry said the bodies will be taken to a crematorium for identification.

Here's what we know so far:

· Flight KGL9268, an 18-year-old Airbus A321-23, belonged to the private Kogalymavia airline, also known as Metrojet, based in west Siberia. Everyone on board was Russian, except for three people from Ukraine and one Belarusian. Most of the bodies recovered so far were severely burnt.

· The plane lost contact with Egyptian air traffic control 23 minutes after it taking off on Saturday morning. It was flying at 31,000 feet when it suddenly began to descend. Flightradar24, which tracks air traffic, said the plane had been descending at a rate of 6,000 feet per minute just before it disappeared from radar.

· Egyptian authorities have recovered the plane's two black boxes, which have been sent for analysis. The authorities have also denied any abnormal signs before the plane disappeared, like a request for a change of route. Kogalymavia has also insisted there were no grounds to blame it on human error, and that the plane was in good working order with experienced pilots.

· The crash site is in the Hasana area in Egypt’s Sinai peninsula, which is mostly a closed military zone, following a long-running insurgency by militants close to Islamic State against Egyptian President Abdel Fattah-el-Sisi’s government.

· Hours after the crash, a militant group affiliated to the Islamic State in Egypt has claimed responsibility for bringing the plane down. Egyptian and Russian officials have refuted these claims, saying experts confirmed that militants could not down a plane at 30,000 feet.

· Three airlines – Emirates, Air France and Lufthansa – have decided not to fly over the Sinai Peninsula until more information is available.

Here's what we don't know yet:

· Investigators are still working to establish the cause of the crash. Russian officials said the plane likely broke up mid-air, but added that it is too early to draw conclusions.

· The possibility of a bomb having been planted on the plane has not been ruled out, reported the New York Times.