What could I do about my toddlers gun obsession?

My almost three year old boy went to a Christmas party with us at some friends house, and they had toy guns. Well immediately my son knew somehow how to use one, even though we have no toy guns in the house. Now that he is at home, he walks around pretending everything is a toy gun and will go back and forth between my husband and I and pretend to shoot us. It's very unnerving seeing how guns are so dangerous and hearing all the stories on the news talk about children that shoot their parents. I know that it's just pretend to him, but where do you draw a line. Am I overreacting what is the best way to handle this situation?