CHICAGO (CBS) – Michigan Avenue downtown was busy and bustling as usual in the midday hours, but a suspicious package shut the road down in the wee hours when a suspicious package was discovered.

The package turned out to be harmless.

Reports first surfaced of a suspicious box near Michigan Avenue and Washington Street around 2:50 a.m., police said.

Police Bomb and Arson Unit officers investigated and found the box to be harmless shortly before 4:30 a.m., Alfaro said. He could not say what the object was, but said it posed no threat to the public.

The northbound lanes of Michigan Avenue at Madison Street were closed as police responded, as were the eastbound lanes of Washington Street at Wabash Avenue, Alfaro said. Crime scene tape was stretched across the sidewalk on Michigan Avenue at the entrance to Millennium Park.

The streets were later reopened to traffic.

The Sun-Times Media Wire contributed to this report.