I'm glad I wasn't home

I live in a ground floor condo in a four unit building. I don't use my front door as my bedroom is on the other side of the unit. The front door is near my living room. I was out running errands and when I pulled into the driveway I noticed the front door of my unit wide open. I immediately pulled over and called 911. I didn't see anyone outside but the police and ambulance were called as it looked as if someone had broken in. I was told to stay in my car and not move until someone got to me. It took about twenty minutes for the police to arrive. When they did, they searched my unit and found no one inside. They found my front door wide open but nothing else out of place. They said it looked like someone had entered but either saw me pull up and ran out the back or got cold feet once they entered. I'm glad I wasn't home when this happened, as who knows what would have happened if I was.