Fire Alarm

So today was a fun little adventure. It started out rather normal though for some crazy reason we were both awake at 7am this morning....mind you it's the one day we get to sleep in and we're up at 7am!!!!! Okay so I guess it didn't start totally normal. We ran some errands. Went to Costco, Henry's and Vons. On our way home from shopping we started to pull up close to our building when we noticed that a lot of people were out in the street. I rolled the window down and could hear the fire alarm going off. We turned around and pulled into our own parking spot and started to unload the trunk. While walking to our place we could tell that our building was the only one with the fire alarm going off. We continued on our way, unlocked our door and walked in and there's an extremely high pitched alarm going off in our house. Our immediate thought was that our alarm triggered the alarm for the entire complex. Peter ran upstairs to check the smoke detectors. I stood still wondering how on earth our alarm could have gone off. We had cereal for breakfast so really nothing could've triggered our alarm. Peter comes back downstairs and we go outside and continue unpacking the car. We ran into our neighbors. I asked if their alarm was going off inside too and they said yes. Then a couple people were like "I heard the alarm going off and figured I needed to change the batteries in my alarm so I did, and that didn't help. Then I went outside and heard the alarm for the entire building." Two people did the same exact thing it was funny. Our neighbor said they called 911 after the alarm had been going off for about 5-10 minutes. The fire truck pulled up. They climbed out and opened the fire panel and looked around the building. They turned the alarm off and we were all thrilled. We could finally go back into our homes. I don't know if they ever figured out what triggered the alarm...it was definitely an adventure for today.