Go outside and talk to one of the people

From Create Your Own Story

You open the door and step out. You try to ask what is wrong with the person limping towards you, but there is no response.

Instead, the person jumps on you like some kind of rabid animal and takes a chunk out of your arm! You quickly slam the door and try to hold them off. The door is banging ferociously. You can't hold it forever!

Lock the door, then find something to barricade it with!

Lock the door, then call 911 and explain the situation to the police!