A worker at a plasma center in the 800 block of Michigan Avenue reported finding a window damaged at the business sometime before Wednesday morning.

The plate glass window is located by the front door of Octapharma Plasma Donation Center.

It appeared someone had thrown a rock at the window, causing it to spread in a web-like pattern throughout the window, according to a police log.

Surveillance video is being examined.

Tina Reed is a reporter for AnnArbor.com. You can reach her at tinareed@annarbor.com, call her at 734-623-2535 or find her on Twitter @TreedinAA.