GREEN BAY, Wis. -- When a pair of helicopters flew over Lambeau Field early in the first quarter of Thursday's preseason game between the Packers and Steelers, it seemed a little late for the traditional flyover.

That's because it was unplanned and unauthorized.

"I was as surprised as anyone," Packers president Mark Murphy said Friday.

It occurred seconds after Jimmy Graham caught an 8-yard touchdown pass from Aaron Rodgers with 11:53 remaining in the first quarter.

It's common to see air traffic near Lambeau Field given its proximity to an airport 4.4 miles away. But flights, such as two helicopters that appeared Thursday night, are typically routed far enough away during game days to avoid causing concern. Rob Demovsky/ESPN

First, one helicopter flew over the stadium from the north, and then a second one followed.

According to the Green Bay Press-Gazette, they were U.S. Navy helicopters.

"That had us scrambling last night," Green Bay Police Commander Paul Ebel told the newspaper.

It's common to see air traffic near the stadium, given its proximity to Austin Straubel International Airport, which is located 4.4 miles from Lambeau Field, but flights are typically routed far enough away from the stadium during game days to avoid causing any concerns.

"The helicopter flights over Lambeau Field last night were not a planned component of the game," the Packers said Friday in a statement. "We are in contact today with the proper authorities to gather more information as to the nature of the flights."

Air traffic control was aware of the presence of the helicopters in the area, Ebel told the Press-Gazette.

"They just happened to make a side trip," Ebel added.