(CNN) -- For 20 minutes, the Southwest Airlines jet was a normal flight from New York to Dallas with 149 people aboard.
The plane was flying at 32,500 feet Tuesday morning as passengers settled in for the three-hour flight.
Suddenly, alarms blared in the cockpit as what sounded like an explosion boomed from the left side of the plane. Oxygen masks swiftly dropped from the ceiling.
What followed was a terrifying sequence of events that ended with one woman dead, seven people injured and an emergency landing at Philadelphia International Airport.
'Everybody was going crazy'
Southwest Airlines Flight 1380 took off from LaGuardia Airport at 10:27 a.m. and landed in Philadelphia about 11:23 a.m.
The Boeing 737 was headed to Dallas with 144 passengers and five crew members. For about 20 minutes, everything seemed calm. Then "a loud boom" suddenly jolted the plane, passenger Marty Martinez said.
"About five seconds later, all the oxygen masks deployed," he said. "I immediately knew something was wrong. It just didn't register what could have been."
Something in the engine broke apart midair and burst through the window, passengers said. A woman was sucked toward the hole where the window once had been as passengers struggled to pull her back in.
"Everybody was going crazy, and yelling and screaming," Martinez said. "As the plane is going down, I am literally purchasing internet just so I can get some kind of communication to the outside world."
Objects flying out
As the plane quickly descended and passengers continued scrambling to pull the woman away from the window, other passengers stuffed clothes and jackets into the hole, said Martinez, who was sitting two rows away from the woman. Those items got sucked out of the plane, too, he said.
"We could feel the air from the outside coming in, and then we had smoke kind of coming in the window," Martinez said.
In the chaos, it was hard to hear anyone. Flight tracking website Flightradar24 estimated the plane descended from 31,684 feet to 10,000 feet in about five minutes.
"It was very loud, so announcements from the pilot or any other crew would not have been heard," passenger Amy Serafini said.
Passenger Matt Tranchin watched the commotion as people tried to help.
"Everyone kind of descended on where this hole was," he said.
He thought about his family and whether he'd see them again. The thoughts were terrifying.
"That I'll never live to see my son born. That I'll never be able to say goodbye to my wife, say goodbye to my parents. But I am. I feel really very fortunate for that," he told CNN affiliate WPVI.
Nurse performs CPR
After trying to pull the woman back for several minutes, a man in a cowboy hat and a second man finally got her into her seat, Serafini said.
A nurse aboard the flight performed CPR.
"We started CPR on the lady, which we continued for about 20 minutes. We were still doing CPR when the plane landed," Peggy Williams said. "We made every effort that we could possibly make to save this woman's life."
Martinez said it was a rough landing, and he wasn't sure if the plane was going to crash. The jet could have been landing on a freeway for all he knew, he said.
"I didn't know if we were going to be running into a building. I didn't know what state the plane or even the pilot was in, if we were in condition to land," he said. "Finally when we ... came to a halt, of course, the entire crowd was (in) tears and people crying and we were just thankful to be alive."
Air traffic call
Before the plane landed, the pilot asked the air traffic controller to send medics to meet it on the tarmac.
"Injured passengers OK, and is your airplane physically on fire?" the air traffic controller asked.
"No, it's not on fire, but part of it is missing. They said there's a hole and that someone went out," the pilot responded.
"Um, I'm sorry, you said there was a hole and somebody went out? Southwest 1380, it doesn't matter we will work it out there," the air traffic controller said.
The controller asked other planes to prepare for the airport to be shut down.
The National Transportation Safety Board said a preliminary look at the engine shows one of its 24 fan blades was missing.
There was evidence of metal fatigue where the blade attached to a hub, according to NTSB Chairman Robert Sumwalt.
"In aviation, there should be inspection techniques and procedures in place to detect something like that. What we want to find out is why was this not detected ahead of time," Sumwalt told CNN on Wednesday.
Metal fatigue is not something that could be seen at a glance, and because it was internal, even a careful maintenance inspection from outside the engine may have missed it, he said. The fan blade spins at several thousand revolutions per minute, so when it was "liberated," Sumwalt said, it basically broke into shrapnel.
It was not an explosion, he said, likening it more to a car's combustion engine throwing a rod, which bangs around the engine.
"More than likely, when the engine fan blade separated, it caused the cowling to separate and end up in this small town northwest of the airport," he said.
The cowling was found about 70 miles from where the plane landed.
Southwest CEO Gary Kelly said the plane was inspected Sunday, but he had no details on what parts were examined. "I'm not aware of any issues with the airplane or any issues with the engine involved," he said.
Sumwalt told CNN that Kelly assured him Tuesday night that Southwest will be conducting "an aggressive ultrasonic inspection campaign for their entire fleet."
The flight data recorder and the cockpit voice recorder have been sent to Washington, Sumwalt said.
Passenger identified as 43-year-old mother of 2
The woman killed was identified as Jennifer Riordan, 43. She worked for Wells Fargo in Albuquerque, New Mexico, according to the bank. Southwest said hers was the first in-flight death in company history.
"This is a sad day and our hearts go out to the family and the loved ones of the deceased customer," Kelly said. "We will do all that we can to support them during this very difficult time."
In a statement, Wells Fargo called her "a well-known leader who was loved and respected."
She is survived by two children and her husband, Michael Riordan, who was once the chief operating officer for the city of Albuquerque, CNN affiliate KOAT reported.
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