CHICAGO (CBS)—Pedestrians in downtown Chicago on Thursday had to dodge large chunks of ice falling from buildings.

As a result of the danger, police closed down some streets, including the intersection at Michigan Avenue and East Delaware Place after sheets of ice began falling from the Hancock Building.

It was a close call for Giselle Castro.

“I’m in shock right now,” Castro said, whose back windshield was shattered by a chunk of falling ice. “I mean if that went through my head I’d be dead.”

Police also closed Franklin Street between Jackson Boulevard and Adams Street for a preventative measure–workers at Willis Tower wanted to safely remove ice that had accumulated on the building.

Despite the city’s safety precautions, pedestrians like Emina Palos were on high alert as they walked around downtown.

“Once you leave the building, you want to see what’s going on,” Palos said. “Want to make sure you’re safe.”

Experts like Daniel Safarik of the Council on Tall Buildings say the falling ice can be partially-credited to modern-day architecture.

“The irony might be that a modernized building with better insulation could be more prone to ice accumulation, assuming there are not other factors,” Safarik said.

Less heat escapes, so building windows, ledges and facades are colder and icier. Then when the outside temperatures rise, ice falls.