take sides / take a side

English as a Second Language English Vocabulary, Grammar and Idioms
1
  1. Police shouldn’t take sides in the ethnic riot when they go to control it.
  2. Police shouldn’t take a side in the ethnic riot when they go to control it.
    Please correct the above.
    Does #1 mean #2?
    Thanks.
2

“take sides”
This is the standard form.

If you “take sides” you pick one side over another.