Two of my credit cards got hit with fraudulent charges the same day. What gives?

This is bizarre and a bit troubling.

Received a call from one credit card company questioning a charge. Turned out to be a fraudulent charge. Account was shut down.

Around dinnertime receive another call about a different card. That one got hit with a fraudulent charge as well. That one's shut down, too.

Now I'm down to one card until I get replacements.

But anyway, what gives? It seems like this is more than just coincidence. What might have happened?