Investigators found evidence of "metal fatigue" in the engine that blew apart from a Dallas-bound Southwest Airlines flight Tuesday, busting out a cabin window and killing one passenger, NTSB Chairman Robert Sumwalt said in a news conference Tuesday night.

The plane, which had departed from LaGuardia Airport about 10:40 a.m. Eastern Time, was forced to make an emergency landing in Philadelphia.

The woman who died was identified as Jennifer Riordan, a Wells Fargo bank executive and a mother of two from Albuquerque, N.M., The Associated Press reported.

"She's the bedrock of our family:" Mother of two died on Southwest Flight 1380

Southwest Airlines CEO Gary Kelly said Tuesday afternoon that he "was not aware of any issues" with the plane prior to the engine failure and that the plane was last inspected Sunday.

"This is a sad day," Kelly said in a news conference at Southwest's headquarters in Dallas.

Seven other passengers had minor injuries, police said. There were 144 passengers on the flight.

Sumwalt said the NTSB was sending a crew to Southwest's headquarters to inspect the airline's maintenance records and that the airline is planning begin "enhanced inspection procedures" for its entire fleet.

Kelly said the 737 plane involved in the incident began flying in July 2000. Planes' engines are overhauled every 30,000 flight cycles, Kelly said, and that the engines on the plane Tuesday were overhauled 10,000 cycles ago.

Kelly would not speculate as to why the engine failed.

"It's premature to link it to other engine failures that have occurred," Kelly said. "Only a handful of similar incidents have happened."

Tuesday's death was the first passenger fatality due to an aircraft incident in Southwest's 51-year history. It was also the first time in Southwest's history that a window on a flight had been knocked out.

"We are deeply saddened to confirm that there is one fatality resulting from this accident," Southwest said in a statement. "The entire Southwest Airlines Family is devastated and extends its deepest, heartfelt sympathy to the Customers, Employees, Family Members, and loved ones affected by this tragic event. We have activated our emergency response team and are deploying every resource to support those affected by this tragedy."

Earlier in the day, Kelly, Southwest Chairman and Chief Executive Officer, released this statement on YouTube.

Go here if you can't watch the video.

"The 737 is the workhorse of the airline industry," Kelly said in the news conference. "We're an all-737 operator."

Kelly said the Southwest crews handled the incident "magnificently."

"The aircraft was at altitude," Kelly said. "This was a very serious event and I'm obviously very grateful there were no other injuries other than the one fatality."

Passengers walked off the 737 plane onto the tarmac using stairs just after 11 a.m. Some passengers on Twitter stated that someone had been partially sucked out of a window before being rescued. Passenger Amanda Bourman told the Associated Press she saw medical workers using a defibrillator on a woman after the plane landed.

Southwest Airlines said there were 143 passengers and five crew members on board. The plane was flying at 32,500 feet and was 40 minutes into its flight when the incident occurred.

The FAA said the crew reported damage to one of the plane's engines, the fuselage, and at least one window. The National Transportation Safety Board will be in charge of the investigation, the FAA said.

Passenger Marty Martinez did a brief Facebook Live posting while wearing an oxygen mask. He posted, "Something is wrong with our plane! It appears we are going down! Emergency landing!! Southwest flight from NYC to Dallas!!"

The Philadelphia International Airport tweeted that the FAA had issued a ground stop for flights entering the city, but it has since been lifted. Passengers should still expect delays, the airport said.

News helicopter footage showed damage to the left engine of the plane and the tarmac covered on foam from fire crews.

Passengers on board posted on social media that the plane was en route from New York City to Dallas when something happened. The Philadelphia airport tweeted that flight 1380 "landed safely at PHL and passengers are being brought into the terminal."

Tracking data from FlightAware.com shows the flight was heading west over New York's southern tier when it abruptly turned toward Philadelphia.

via GIPHY

Chris Mainz with Southwest Airlines released this statement right after the incident:

We are aware that Southwest flight #1380 from New York La Guardia (LGA) to Dallas Love Field (DAL) has diverted to Philadelphia International Airport (PHL). We are in the process of transporting Customers and Crew into the terminal. The aircraft, a Boeing 737-700, has 143 Customers and five Crewmembers onboard. We are in the process of gathering more information. Safety is always our top priority at Southwest Airlines, and we are working diligently to support our Customers and Crews at this time.

A Collin County kindergarten teacher and firefighter have confirmed that they were on the plane.

Dallas-based Southwest Airlines has never had a major accident, but a similar engine issue happened on a Southwest Boeing 737-700 in August of 2016 as it flew from New Orleans to Orlando. Shrapnel from the engine created a hole above the wing, and passenger oxygen masks were deployed. The plane landed safely in Pensacola, Florida.

In that incident, the NTSB determined that one of the engine's fan blades broke off during the flight. Crack lines consistent with metal fatigue were found on the blade.

The NTSB has sent a crew to Philadelphia for an "extensive investigation." Officials said in a 2 p.m. press conference that they understand the issue involved the failure of the left engine.

Police said Tuesday that the plane's passengers are being assisted by the American Red Cross and crisis counselors.