Mike Larson was supervising his second-grade students at recess in Chaska when he glanced up at a triangle-edged aircraft cruising above them. Kyle Heino tweeted a picture of its L-shape cutting into the Shakopee sky. And Daryle Just-Fleck peered at its gray underbelly in Mahtomedi.

Minnesotans going about their daily routines were caught off guard Wednesday when they caught a rare sight of a B-2 stealth bomber soaring above them.

They called their relatives in the Air Force, lit up social media and speculated about why the military aircraft was traveling in their airspace.

Turns out the bomber aircraft capable of carrying nuclear munition was on a routine training mission from its base at the Whiteman Air Force Base in Missouri. The Air Force keeps its fleet of 20 B-2 bombers, which cost $1.157 billion apiece, at Whiteman.

“This training mission spanned several states over the central U.S., including Minnesota,” said Matthew Van Wagenen, a Whiteman spokesman. “The aircrew were asked to fly at a lower altitude by Air Traffic Control to avoid traffic in Minneapolis airspace.”

The bomber has lowered infrared, acoustic, electromagnetic, visual and radar signatures that help it pass through defensive systems.

Heino, 39, didn’t hear a sound as the bomber soared 5,000 feet above him. He spotted it while helping prepare Canterbury Park for the Festival Palomino.

“I called my friend in the Air Force who told us what it was,” he said. Heino snapped pictures of the B-2 Spirit and posted them on social media.

Just-Fleck, 45, heard the bomber’s rumbling and stepped out of his Mahtomedi garage with a friend to watch it in awe.

Larson, who also posted photos on Twitter, said it was a typical recess at Jonathan Elementary until he looked up to see the plane. Larson, dean of the school, and all the adults present watched it with fascination. The second-graders, he said, were less impressed, looking up only briefly before resuming their play.

“Typically you might hear an airplane now and then,” he said. “All of a sudden there was this large aircraft coming over the top [of the school].”

The Star Tribune's Shari Gross captured this short video of the flight when the bomber passed over the Vikings training facility in Eden Prairie.

Others in the Twin Cities captured photos of the bomber, too. The aircraft is designed to penetrate anti-aircraft defenses and flies with a crew of two.

Really cool stealth bomber overhead at recess today. pic.twitter.com/juDxnsOA6F — Mike Larson (@MrLarsonJES) September 17, 2015