Air Force officials say an unmanned mini space shuttle landing at Kennedy Space Center caused a sonic boom that shook central Florida early Sunday.

The Air Force confirmed to the Orlando Sentinel that its X-37B craft caused the boom as it ended its nearly two-year-old secret military mission.

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Many experts believe the craft, launched in 2015 from Cape Canaveral Air Force Station, carried intelligence-gathering equipment, the newspaper reported.

“[It] is an experimental test program to demonstrate technologies for a reliable, reusable, unmanned space test platform for the U.S. Air Force,” the military said in a news release.

The sonic boom from the 29-foot-long, 11,000-lb. mini shuttle was reportedly heard as far away as Tampa and Fort Myers.

“Didn’t sound from where I live [like] a sonic boom,” said Cherie Doughan, who heard the sonic boom near Cape Haze in southwest Florida. “Sort of unnerving with things the way they are world wide.”

The Sentinel added that another X-37B mission is scheduled to launch from Cape Canaveral later this year.