Yikes - is there a virus spreading???
My brother called me from his place in NC over the weekend to tell me of the commotion at his place. The smoke detectors started blaring at 4 a.m. They are all centrally wired together, so when one goes off, they all do. They checked the place with a fine tooth comb and couldn't find anything, so reset them and went back to bed. A half hour later they went off again, so he called 911 (you'll see why). They had the fire marshal, rescue squad, firemen, and local police swarming the place. They brought in a heat sensing camera and went thru the house and found nothing and came to the conclusion that it was one of the detectors that is faulty. My brother put in a call to his contractor that installed them a year ago, to come find the problem. NOW!!!
You see - he's only lived in that house for a year. He bought it about 2 and a half years ago, and was moving in a little at a time from his home in FL, when there was an electrical fire when no one was there and he was at his FL place. It was completely gutted, and all that was left standing was the outside brick walls and the brick fireplace. The place was rebuilt - custom specs and upgrades, and is twice the place he originally purchased. Fortunately, it was well insured.
So that's why he called 911. I probably would have called when they first went off. Most of the firemen that were there over the weekend, were also at the first fire, and said he definitely did the right thing by calling them.