Barricade

I've barricaded myself inside my house. Boarded up the windows and the doors. I'm in my attic because it has a ladder that can be retracted. I have enough food and water to last for three days. I told Mom to stay at a friends house at least for a few days. I'm still not sure what it was,but it was white and bald. It looked almost human, but crawled like an animal. when it spotted me I ran for the front door and it chased me. it was  very fast but i had a huge head start.  Does anyone know what this thing is? I can still hear it scratching at the front door.