An F-16, front, and an F-35 from Luke Air Force Base.

Several days of seemingly random “booms” heard in various parts of Tucson and Southern Arizona left residents wondering on social media if an alien invasion had begun.

But no, extraterrestrial creatures have not made contact. The official explanation, which came from Luke Air Force Base in Phoenix, might disappoint fans of Fox Mulder from the “X-Files.”

The booms were heard by residents near East Broadway and North Craycroft Road; North First Avenue and East Glenn Street; and South Mission Road and West Los Reales Road, among various other locations in and around Tucson. They also were reported in Picture Rocks, Sells, Sierra Vista, Cascabel, and Willcox, according to social media posts.

Many of the posts reported booms, or a series of three booms, and rumblings that shook window panes Wednesday afternoon between 3 p.m. and 8 p.m. Others said they had heard them several days before and more booms were reported Thursday.

The booms prompted at least one woman to run outside and check on her children. They also spooked horses and shook the windows at a day care.

The U.S. Geological Survey reported no seismic activity in the area. The National Weather Service said it hadn’t seen any weather phenomenon to explain the booms. The Pima County Sheriff’s Department had no explanation for the booms. Davis-Monthan Air Force Base and Fort Huachuca reported no munitions or flight activity that would cause the noise.

Aircraft from Luke Air Force Base are the likely cause of the booms, the base said Thursday.

The base is conducting an exercise with the Singapore air force, according to Luke spokeswoman Kiley Dougherty. That exercise includes flying through airspace near Tucson and over the Barry M. Goldwater Range near Yuma.

The exercise, known as Forging Sabre, is a biennial operation with the Republic of Singapore Armed Forces, according to a Nov. 27 news release from Luke Air Force Base.

The exercise will run until Dec. 11 and residents should expect more flying operations on nights and weekends, according to the news release. Aircraft involved in the exercise include F-16 Fighting Falcons, F-15E Strike Eagle, and Heron 1UAS.

Contact reporter Curt Prendergast at 573-4224 or or on Twitter @CurtTucsonStar