Southwest Airlines announced today that they are grounding 79 planes after 3- to 4-foot hole opened in the fuselage of one its planes mid-flight, forcing the plane to make an emergency landing.

The airline will be inspecting the 79 Boeing 737 fleet as part of the investigation into the incident, which happened on a flight from Phoenix to Sacramento, Calif. After the plane landed safely at a military base in Yuma, Ariz., authorities there found a hole in the top of the aircraft, CNN reports.

Investigators are calling it a “depressurization event” and are trying to figure out what caused it. They’re grounding the other planes to “begin an aggressive inspection effort in cooperation with Boeing engineers,” according to a company statement.

“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.

Not surprisingly, passengers on board the plane were afraid for their lives.

“We were in shock,” passenger Debbie Downey told CNN Saturday. “We were in row 16 and my husband and I could see blue sky … the wiring, the cabling. It actually was terrifying.”

She said. “a lot of people were crying and holding hands” but had trouble hearing due to the noise of air rushing through the plane’s opening. “It was very, very scary.”

No customers were hurt, but one flight attendant fell and had a minor injury during the descent.

Check out the video from CNN of passengers describing the incident:

Southwest to ground 79 planes after hole prompts emergency landing [CNN]

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