Do not leave your keys behind!
1. We tried every entrance, but all the doors were locked, which is great, but not in this situation!
2. We tried to remain calm, it was hard when we were outside with two kids, it was getting cold, and our neighbors were out of town
3. We called a locksmith near our house and we got help within 25 minutes
The moral of the story, make sure that you have your keys with you before closing the doors AND make sure that your parents or siblings have a spare key to your house. It's quite expensive to hire a locksmith to open your door in less than 5 minutes!