CHICAGO (CBS) — A suspicious package shut down Michigan Avenue at the Chicago River for a while Monday afternoon.

The package was found on the riverwalk below the Michigan Avenue bridge.

Lower Wacker Drive was also closed.

Chicago police, fire, bomb and hazardous materials units were on the scene to investigate.

The bridge was reopened around 1:30 p.m. Battalion Chief Mitchell Crooker says they tested it, and it turned out to be a drain cleaner, which was safe if contained, which it was.

When asked if they use the substance for cleaning, Crooker told Newsradio, “I don’t know. All I know is that something that doesn’t appear to belong sitting where it is hazardous and we treat it as such.”

The drain cleaner came in a bottle that said “liquid fire” on it.

Chief Corker says the response is based on the times and recent events.

“It is 2013, that is the environment that we live in,” said Crooker.