I would have him seen for his anxiety. Talk to a couple of children's therapists until you find one who you think has a good grasp of the situation and a calm attitude, and go from there.
They have two young children themselves and they are adapting to the situation. They have stepped up protection measures and I think their children sleep with them anytime they want anyway. My son has always been a "scarredy cat' type. But this has just set us back several years. It is difficult when he won't dress himself or play alone -we would never leave him alone for any length of time. Our busines is right on the property. I just wonder what I can do to help him. He is just scared of any unknown person- breaking in, trying to hurt him.
I am wondering why it would affect him so drastically as he only saw the robber coming out, is there more to the story, what happened after he saw the robber ? what did the friends family have to say ?