Would this cyber assassination constitute an act of war?

And what followed was kind of a spontaneous call for a response to this murder, people started gathering in Exarchia.

The immediate cause was of course the assassination in Sarajevo of the Austrian Archduke Franz Ferdinand on June 28, 1914, by a Bosnian Serb nationalist named Gavrilo Princip.

But even so, the assassination led Austria to issue an ultimatum to Serbia, whereupon Serbia accepted some but not all of Austria's demands,