The Federal Aviation Administration is investigating an incident on a Southwest Airlines flight this week during which passengers said they heard from the cockpit “we’re going down” before the plane descended rapidly.

Flight 3426 was headed to the Raleigh-Durham International Airport in North Carolina from Tampa late Tuesday when passengers said a cabin pressure problem prompted the cockpit alert.

Southwest said the captain was informing flight attendants that the plane was descending to deal with the pressurization issue, but the message went out on the public address system. Passengers said it was a scary experience.

Phyllis Westerman told WSB Radio that she saw flight attendants panicking when oxygen masks would not deploy. “My husband and I heard a flight attendant panicking and yelling into the cockpit, ‘Manually deploy them!’ and nothing was happening. That is when the pilot came on the PA system [saying] that we’re going down.”

Passenger Shelley Wills told WTVD-TV in Raleigh-Durham, which first reported the incident, that passengers at first didn’t believe what they were hearing. “And everyone is looking around like, ‘Is this a joke? Is he serious?’” Wills said. “And then you felt the nosedive.”

Another passenger, Grace Stroud, told CNN that she heard, “’We’re in trouble; we’re going down’” on the PA system.

Wills said passengers all around her started pulling out cellphones to call loved ones. She said texted her daughter and husband, “I love you Alyssa. My plane is going down.”

Southwest spokesman Brad Hawkins told The Atlanta Journal-Constitution the flight had 96 passengers and a crew of five. He said as part of the procedure to resolve the cabin pressure issue, the captain notified the crew that the plane was going to a lower altitude just before “an unplanned but controlled descent.

“The maintenance issue was resolved before the flight safely landed at Raleigh-Durham,” Hawkins said Thursday.