why do smoke alarms go off without smoke

Last night around 2am, all three of the hard-wired (not battery powered) smoke detectors in our apartment went off. We were unable to use the reset buttons and had to physically disconnect them to get the alarm to go off. There was no smoke or other sign of a real threat that could have set them off. I suppose it could have been low levels of carbon monoxide and that will be the first thing we'll try to rule out tonight.


Any other ideas as to what could have caused this and what we should do? I've had smoke alarms go off when they run out of batteries before, but never anything like this.
Just woke up around 2AM to the most horrific, freaky, shrill noise of my alarm. I thought it was a driveway sensor but I later found out it was an alarm.


These are hardwired in with the 10+year? battery. Brand new 6 months ago. Never had any fluke issues, beeps, etc. Just this random one occurrence last night. I was beyond startled. It made me sick. I'm still shaken from it this morning. I'm worried I'd just freeze up if the alarm had kept going but it only last enough to wake me up and jump out of bed before it stopped on its own.


Are all modern hard-wired alarms made so if one has an issue, they all sound? I was too delirious to tell if it was 1 or the hall, office, and bedroom at once. I swear if it happens again I am going to destroy the things and buy a battery powered standard one for the hall. Being a modern alarm, I am assuming it's the photoelectric type that apparently a spider can set off?


Lovely. I'm going to buy some compressed canned air and blow the 3 upstairs and the one in my basement this evening. The one in the basement I believe still has the plastic hair net on it from factory to keep it clean. which I realize maybe made things worse. The only other theory I have is my driveway alarm receiver radio wave triggered one alarm.


I've had it set up for a couple weeks without a problem, though, so happening now makes no scientific reasoning. The dust or spider is the only logic I can find out of this, being new - flawless sensors the past 6+ months. Wish more people would report back in if they had this happen once and never again, or if it occurred more than once and cleaning the alarm solved the issue.