Turns out the cause was a motor that's part of the ventilation system under the raised floor. No one was hurt and things returned quickly to normal about 1 a.m.
Our own assignment editor, Dani Fink was right on the game after calling the fire department, she had her camera ready and snapped some pictures which you can find on her blog: Swing By and Spray.
Never a dull moment at the WKYC Digital Broadcast Center.