Heading to work at 5:30 a.m. on Interstate 5, downtown Seattle. Heard a loud "POP" like gunfire. First thought it was a sniper, really!! Roads are barely traveled, I wasn't under an overpass, and no semi in front of me carrying gravel. The tempered glass appeared to break all around the seal. Glass flying behind me as I drove. Parked it and duct taped around outer edges of the sunroof, trying to hold glass in place and hoping it wouldn't fly off in one sheet and hit the car behind me. Luckily, I pulled the shade which prevented the glass from falling on me and the interior of the vehicle. I called the insurance company, need a rental car for a couple of days. Let's not forget the deductible. Glad I googled "exploding sunroof". I am not the only one with this problem. And, yes my co-workers friends and family said it had to be a rock or someone dropping something from an overpass. The exploding sunroof had everyone baffled to include the repair shop and car dealership. I'm glad no one was hurt. It happens more often than I thought.