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The Middlesex County Sheriff 's Office is a law enforcement agency which serves the 54 cities and towns of Middlesex County , Massachusetts , United States .
 Middlesex, Middlesex County , Massachusetts
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Middlesex, Middlesex County , Massachusetts