CO Alarm

About 2 weeks ago we bought fire detectors and a CO alarm. We never hung them, the batteries are in them but they sit, all three of them in our living room. And tonight during dinner our living room table went off. the CO alarm. So we called my father in law who is hazmat and would know about these things, and he said we should call 911, which seemed a bit extreme but since we had the alarm and it went off and we had Claire in the house, we thought we should call, cause it would be a shame for us to all die and then they all say that we had the alarm. So the fire department came and opened all our windows and told us that we have a 30 parts per million of CO. (which is low) Here they are, our first 911 call since our marriage. We took pictures:
So they left and we reset the alarm and it went off again... so we'll call 911 again... I'll keep you posted but for now we are sleeping with windows opened and that will keep the levels at 0. All is safe, we just need to find out where this CO is coming from.