There's a well-known proverb in Persian, which, translated literally, goes like this:
Where there's fire, wet and dry burn together.
The original being ".وقتی آتش موجود باشد) تر و خشک با هم می سوزند)"
In a large forest fire, both dry wood that can be ignited easily and wet wood that's hard to burn, burn. A good example of a context it's used in would be a principal punishing a whole class because of what few perpetrators did — so students that didn't deserve to be punished, (that is, the wet) burned alongside the ones that did. (that is, the dry)
Is there a proverb that would express the same thing in English? More specifically, is there a proverb that would convey the innocent receiving undeserved punishment?