PHILADELPHIA — A Southwest Airlines jet with a damaged engine and window made an emergency landing at Philadelphia's airport Tuesday, and one passenger was critically injured. A former federal investigator theorized the plane blew an engine and the shrapnel hit the aircraft.

Seven other people aboard the Boeing 737 that was headed from New York's LaGuardia Airport to Dallas' Love Field were treated for minor injuries, according to Philadelphia Fire Commissioner Adam Thiel. He said there was a fuel leak in one of the engines when firefighters arrived and a small fire was quickly brought under control.

Southwest said there were 143 passengers and five crew members on board the plane and most walked onto the tarmac after landing around 11:20 a.m.

"I just remember holding my husband's hand and we just prayed and prayed and prayed," said passenger Amanda Bourman, of New York. "And the thoughts that were going through my head of course were about my daughters, just wanting to see them again and give them a big hug so they wouldn't grow up without parents."The Federal Aviation Administration said that the plane landed after the crew reported damage to one of the engines, along with the fuselage and at least one window. They didn't immediately explain what went wrong. The National Transportation Safety Board sent investigators to the airport.

Bourman said she was seated near the back and was asleep when she heard a loud noise and oxygen masks dropped from the ceiling. She said the plane was fairly quiet because everyone was wearing a mask, while some passengers were in tears and others shouted words of encouragement.

"Everybody was crying and upset," she said. "You had a few passengers that were very strong and they kept yelling to people, you know, 'It's OK, we're going to do this.'"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!!" After the plane landed, he posted photos of a damaged window near the engine.

Bourman said that everyone started yelling to brace for impact when the plane started to land. Everyone clapped and praised the pilot after he set the aircraft down.

Bourman said she saw emergency medical workers using a defibrillator to help a woman who was taken off the plane. Thiel declined to release any other details about the woman's condition.

Bourman said that she saw a man in a cowboy hat rush to cover the broken window and that the man had a bandage around his arm after the plane landed.

Passengers did "some pretty amazing things under some pretty difficult circumstances," Thiel said.

Tracking data from FlightAware.com shows Flight 1380 was heading west over New York's southern tier when it abruptly turned toward Philadelphia.

Southwest has about 700 planes, all of them 737s, including more than 500 737-700s like the one involved in Tuesday's emergency landing. It is the world's largest operator of the 737. The Boeing 737 is the best-selling jetliner in the world and has a good safety record.

John Goglia, a former NTSB member, said investigators will take the Southwest engine apart to understand what happened and will look at maintenance records for the engine.

"There's a ring around the engine that's meant to contain the engine pieces when this happens," Goglia said. "In this case it didn't. That's going to be a big focal point for the NTSB — why didn't (the ring) do its job?"Goglia said the Boeing 737 is a safe plane but engine failures occur from time to time.

"We're pushing the engines to produce as much power as possible," he said. "We're right on the edge. Sometimes they fail, and that's why the containment ring is there."The engine failure was reminiscent of a similar event on a Southwest Boeing 737-700 jet in August 2016 as it flew from New Orleans to Orlando, Florida. Shrapnel from the engine left a 5-by-16-inch hole just above the wing. Passenger oxygen masks dropped from the ceiling. Pilots landed the plane safely in Pensacola, Florida.

Investigators with the National Transportation Safety Board said one of the engine's fan blades broke off from the hub during the flight. The broken edge of the blade showed crack lines consistent with metal fatigue.

Koenig reported from Dallas. Associated Press writers Kristen de Groot and Claudia Lauer in Philadelphia contributed to this story.

AP