Terrifying.

Last night, at 1:57 a.m. Jared and I were dead asleep. At 1:58 a.m. we were not. We were rudely awakened by all of our fire/carbon monoxide alarms blaring. Not only were they blaring, but we have high-tech alarms that also yell "FIRE" and "CARBON MONOXIDE" intermittently between the alarms.
Anyway, we sprung awake, and all I could think was "our house is on fire!!! What should I grab!!" which is a terrifying thought let me tell you. But Jared jumped up and turned the light on and there was no smoke. He quickly ran around the house, and there was no smoke. Phew. But then the alarms all started yelling "CARBON MONOXIDE!" and I freaked. We (and by we, I mean Jared...because I was kind of just a little freaking out at this point) ran around and opened all the windows and doors, and Jared worked on turning the alarms off. Seriously I bet they woke up our neighbors on both sides they are so loud.
I immediately jumped on the internet to figure out what to do. I didn't want to call 911 because there wasn't a fire, but I guess I never learned what to do if the carbon monoxide alarm goes off. I came to the conclusion that we needed to check the pilot lights in our hot water heater and furnace and check for a "dull yellow flame" which meant there was carbon monoxide, then I decided I needed to call the fire department so they could come check the levels.
So I semi-calmly called up the station, and told the nice man that answered the situation and he said it was the right thing to call and they'd send out someone to check for carbon monoxide levels.
Jared and I waited outside in the (FREEZING) garage, with the door open, waiting, and in a few minutes a fire truck pulled in front of our house. It was now about 2:25 a.m. and thank goodness they didn't have their sirens on.
Three firemen got out and started walking through the house and one had a little device to check the levels. We told them everything that happened, and they checked all over the house and got a "0" on the carbon monoxide levels, which was relieving, but also made us feel a little silly. Luckily they were all very kind and just wanted to make sure we were ok, and kept reassuring us that calling was the right choice, better to check it out then go back to bed and not wake up. They said what probably happened was one of two things. Either a bug walked across the sensor of one of the alarms, which set it off, and then it set them all off, or one of the batteries was dying and set it off, though I don't think so because they never chirped, they just immediately went into "GET OUT OF THE HOUSE YOU ARE GOING TO DIE" mode.
So the three nice men left, and we thanked them profusely, and we proceeded to go back to bed. It was now 2:52 a.m. and you can bet it took us a while to calm our nerves and go back to sleep.
Moral of this terrifying experience: Vacuum out your alarms (especially if they are sensitive, high-tech ones) once a month so you don't practically pee your pants in the middle of the night thinking you are going to die.
The end.