You can use "in all such situations" in all such situations that allow it.

You can’t. Because both “all” and “such” are predeterminers, you shouldn’t put them together.

Hi you need to have a sentence before this to explain what happened before hand. Example: People were shopping in the market place, when they heard a loud bang. In all such situations they knew that a bomb had gone off, so they took shelter where they could.

I'd use 'in all of these situations' or 'in all situations like these' because it sounds more natural, but I'm fairly certain in all such situations works, too.