A Southwest Boeing 737 like this one made an emergency landing Friday. (Photo by Atomic Taco via Flickr)

But that's exactly what passengers on a Boeing 737 whitnessed on a Southwest flight from Arizona to Sacramento Friday.

While in the air, passengers heard a noise and a 3-to 4-foot hole appeared in the fuselage of the plane, exposing wiring, insulation and blue skies to passengers. Fortunately, the plane safely made an emergency landing at a Yuma, Arizona military base.

One flight attendant and at least one passenger were treated for minor injuries at the scene. But no one had to be transported to the hospital. There were 118 passengers and five crew members on board the flight.

"The safety of our Customers and Employees is our primary concern, and we are grateful there were no serious injuries," said Mike Van de Ven, Southwest's executive vice president and chief operating officer. "We have launched personnel to Yuma to begin the investigation process with the NTSB, FAA, and appropriate parties to determine the cause of the depressurization."

In response to the incident, Southwest said Saturday that it will ground 79 planes to inspect for "aircraft skin fatigue." The inspections will force the cancellation of as many as 300 flights Saturday.

Listen to passengers describe the ordeal and take a look at the hole in the CNN video below: