Why do Orthodox Jews have metal bars in front of their windows?

Hi all,

This is a question out of genuine curiosity.

I recently moved into the Wiedikon neighborhood of Zurich. There is a significant orthodox Jewish community here.

While walking around, I have noticed that a lot of the orthodox families have their windows barred with metal grids. I usually see these bars at ground level as a deterrent for criminals, but these bars are on the upper levels?

Is there a specific reason for that? Or am I interpreting too much into this.

Either way, love my new neighborhood and the Jewish bakery is really great.

Thank you!