We now know what caused that window-rattling "ka-boom!" that startled people across several counties in southwest Iowa and southeast Nebraska about 11 A-M Wednesday. Officials say it was a sonic boom caused by a high-flying F-16 fighter jet. Lieutenant Colonel Les Carroll is spokesman for the South Carolina Air National Guard — and claims responsibility.

Carroll says, "Yeah, an F-16 from the South Carolina Air National Guard did create the sonic boom." Police in the Omaha-Council Bluffs area fielded hundreds of calls from concerned residents. Carroll says the pilot was flying high to avoid the weather and was descending to prepare for landing in Sioux City when he broke the sound barrier.

He says, "It wasn’t in violation of any Air Force regulations but we do apologize to the people for any anxiety that it might have been caused." Carroll says it was an isolated incident. He says: "People can be assured that nobody was in danger. There was nothing unusual about the flight except the pilot exceeded the sound barrier." The boom was heard by thousands of people on both sides of the Missouri River, from Tabor in southwest Iowa’s Fremont County to Arlington, northeast of Omaha.