According to Spaceweather.com, the event occurred at 11:35 Universal Time on September 10. Dan Peterson of Racine, Wisconsin, observing through a 12-inch Meade telescope, observed a white flash lasting for 1.5-2 seconds. George Hall of Dallas, Texas was capturing a video of Jupiter at the time, which also captured the event.
It's believed that the explosion was due to a comet or small asteroid collision. Similar events were observed in the past, in June and August 2010.