A Qantas jet made an emergency landing in the Philippines early Friday morning after a gaping hole opened in the plane's fuselage following what was described as a large bang onboard. No one was injured and authorities are investigating the cause.
The Boeing 747-400, en route from London to Melbourne, Australia, plunged some 20,000 feet over the South China Sea after what the pilot called an "explosive depressurization." The 345 terrified passengers escaped safely, but many of them reported vomiting.
"There was an incredibly loud bang for no logical reason at all," passenger Phil Restall told reporters. "The oxygen masks were deployed. Crew and we put masks on. Pilot took us down very quickly."
One hour after the flight took off from a layover, passengers heard the noise, followed by a massive swirl of debris through the cabin, and they said they could see into the luggage hold below.
Watch "World News with Charles Gibson" at 6:30 p.m. and "Nightline" at 11:35 p.m. ET for the latest developments on this story.
The 17-year-old jet had been "plagued by a history of corrosion," according to Australian newspaper the Daily Telegraph.
The plane had been refurbished with a new interior in March, and engineers noted "a lot of corrosion during the refit," according to the paper.
Experts believe the hole was the result of metal fatigue or an internal explosion. U.S. law enforcement and intelligence officials, however, say there is "no sign" that a bomb was used.
Current and former National Transportation Safety Board investigators told ABC NEWS that Qantas has an excellent safety record. They speculated that in addition to metal fatigue or an explosion, damage could have been done to the plane on the ground while the plane was loaded with cargo and catering items.
The hole, measuring about 6 feet by 13 feet, was on the aircraft's underside near the right wing.
As the plane plummeted from 30,000 feet oxygen masks were deployed.
"There was an almighty crack you could hear something happened and then the oxygen masks fell down and you started dropping down ears popping, that sort of stuff," said passenger Owen Tudor.
One woman seated away from her boyfriend on the plane said everything happened so quickly she did not know what was happening.
"I thought maybe he's gone. I don't know, I had no idea, I heard there was a hole somewhere. But I didn't know what was going on," said Australian Marina Scffidi.
Chief superintendent Atilano Morada of the Philippine Aviation Security Group said his officers, including explosives experts, may assist in the investigation.
"So far, they don't want us to touch it, so we will respect the aircraft owner. But we will make our personnel available if they need assistance in the investigation," he told the Associated Press.
ABC News aviation consultant John Nance said the hole could have been caused by an "incendiary device," but U.S. officials at the TSA said there was no early indication it was a terrorist attack.
"The question is did we have something that blew up in that cargo compartment?" Nance asked on "Good Morning America." "When you look at pictures from outside you can see the metal pushed out and around that indicates something blew out from inside -- either a weakness in the structure, which would be very, very rare, or an incendiary device."
Nance said once the hole occurred, all of the safety systems worked exactly as they were supposed to.
"Quite frankly there is no difficulty at all [in handling the plane] because there were no flight controls involved. Very routine thing once they had the rapid depressurization. Any of us would say this was not a heroic thing but good training and a system that worked exactly as designed."
In 1988, an Aloha Airlines Boeing 737 had an 18 foot section of the fuselage roof and sides torn away, resulting in a flight attended being ejected from the aircraft. Investigators later determined that disaster was caused by metal fatigue.
ABC News' Lisa Stark, Pierre Thomas and Richard Esposito contributed to this report.