The attacks have generally been blamed on Islamic militants.
Police said that they had already arrested 13 militants they said had been preparing to provoke Mayday violence.
Hundreds of suspected militants have been arrested in the campaign.
The few revolutionary militants who were leading the strike were doubtless a pole of regroupment for some of them.
I can give you a direct assurance that they are - or in many cases were - in no sense Islamist militants.