An Air Algerie flight en route to Algiers lost contact 50 minutes after take off from Burkina Faso, according to Algeria's APS state news.
More top news
Two knives were found at the scene in Islington, North London, and the suspects fled on foot before being arrested.
The violence began after a counter-protester allegedly doused a female rally organiser with pepper spray.
As temperatures climb through the day, the warmest spots are likely to be across western parts of Northern Ireland and western Scotland.