Terrible news coming across the wires in the past hour or so
Conspiracy theorists will be out in force but the aircraft's altitude suggests that it could not have been struck from the ground. That doesn't however rule out an internal explosion of some kind
Update: 11.20 GMT- Egyptian officials say all passengers were Russian and the black box has now been found. The crew reported "technical difficulties". President Putin has ordered a full investigation and declared a day of mourning tomorrow. The BBC now reports that the flight's captain had asked for an emergency landing at El Arish airport, but the plane did not make it and crashed 50km (30 miles) away. People in Egypt are mainly exploring a technical fault in the plane.
More from the Beeb here and our thoughts/condolences are with all affected
Our thoughts also with the people of Romania who will have 3 days of mourning following the awful nightclub tragedy which has killed 27 people so far and left many more injured
Not a happy start to the week-end