jcs1118

Got in the car on a cold morning (10F). Went to start it. It turned over like normal for a few seconds, then a pop, then shut down. Tried to re-start with start button. Nothing. Tried to start with the key and it tried to crank. I think the starter is trying, but I don't think it's turning. Timing chain jump? Car has 100,000 miles on it. Before I tow it to a repair shop, I'd like to get an idea of possible causes.