The correct answer is: no article.

The word "police" is a common noun, which means it refers to a general class of things. Common nouns are not typically preceded by articles.

In this case, the speaker is calling for help from the police in general, not from a specific police officer. Therefore, no article is needed.

Here are some other examples of common nouns that are not typically preceded by articles:

  • water
  • air
  • food
  • money
  • time
  • love
  • life

Note that there are some exceptions to this rule. For example, if the speaker is referring to a specific police officer, they might say "Call the police!" In this case, the article "the" is used to identify the police officer as an individual.