Last night my wife and I were finishing dinner around 7:45 when we heard a prominent "boom." We thought something hit the house - the javelina nose up around the doors occasionally and knock things over. Perhaps a sudden gust of wind tipped over patio furniture? But a tour around outside found nothing.
This morning, the newspaper says there were reports from all over the west side of Tucson (we live in the Tucson Mtns, about 4 miles west of downtown) of the boom and no obvious explanation for it. Speculation is that it was a sonic boom.