(CNN) Throughout 2016, terror attacks have ripped apart small towns and big cities in the Middle East, Africa and Europe. This weekend brought no respite.

Three deadly blasts in major cities thousands of miles apart targeted sites where people gather for life's daily rituals.

Different groups claimed responsibility for two of the attacks, carrying them out in the name of different political and religious causes.

In each of the three explosions, ordinary people paid the ultimate price, casualties of ongoing battles where there is no front line, no readily apparent uniform that denotes the combatants as friend or foe, and little anyone can do to ensure security.

By now, the message is clear: No place is truly safe, whether it's a church, a park, a school or a busy street.

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