The municipality said a crossing guard first noticed the agents around 8:30 a.m. between John Street and Birch Avenue and they were believed to have been affiliated with ICE.
Two men were taken into custody, one who was on his way to work and the other on the way back from taking his children to school, officials said.
Officials said ICE was unable to provide reasons why they were detained.
Princeton police said they do not participate in federal immigration enforcement.
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