A window on WMAQ‘s street-level studio was shattered Saturday morning.

It is unclear whether the damage was connected to the NATO summit in Chicago but it occurred as thousands of demonstrators filled the city’s streets over the weekend to protest the actions of the collected world leaders.

The NBC station reports that security guards on patrol at the time responded to the sound of shattering glass but did not see anyone when they arrived at the scene of the crime.

Police are investigating the incident, which was reported around 10:30 a.m.

Here’s raw video of the broken window…