UPDATED 05/18/12 10:34 a.m.
CHICAGO (CBS) — Michigan Avenue was briefly shut down between Lake and Madison streets due to police activity.
The road had reopened as of 10:25 a.m., and crime scene tape had been removed.
Police had shut down both sides of the long stretch of Michigan Avenue – much of which is alongside Millennium Park – as of 10:20 a.m.
CBS 2’s Kris Habermehl reports someone apparently heard a detonation or explosion reminiscent of fireworks at the scene, but there were no reports of any explosives being found.