A white police officer in Colorado has been placed on leave while the authorities investigate why he detained a black man holding a trash clamp in front of the man’s home.

The man, who repeatedly told officers that he had been picking up trash in front of the building where he lives and works, was not taken into custody or booked on suspicion of a crime, the police said, but the episode late last week has caused anger and concern in the liberal and largely white city of Boulder, Colo.

At a City Council meeting on Tuesday, residents reportedly clacked trash grabbers as Chief Greg Testa of the Boulder Police Department briefed officials on what had happened and announced that the officer had been placed on administrative leave.

“This is an extremely concerning issue and one we are taking very seriously,” Chief Testa said.

The college town’s population is about 100,000 — 81 percent white and less than 2 percent black, according to census data. And at Tuesday’s meeting, city officials — most of them white — found themselves grappling with issues of structural racism, bias and restorative justice.