MANILA, Philippines — Australian investigators on Saturday began examining a Qantas jumbo jet which had to make an emergency landing after a large hole opened on its fuselage, a Philippine aviation official said.

The Boeing 747-400 was cruising at 29,000 feet with 346 passengers Friday when it was shaken by an explosive bang. The plane descended rapidly before landing safely minutes later at the Manila airport.

There were no injuries among the passengers and crew, but some of the passengers suffered nausea.

Ruben Ciron, chief of the Civil Aviation Authority of the Philippines, said four specialists from the Australian Transport Safety Bureau were still inspecting the aircraft to determine what caused the damage.

Qantas Chief Executive Officer Geoff Dixon told reporters Saturday he was "horrified" after seeing pictures of the aircraft's gaping hole. He said it was too early to speculate on what caused the damage.

"There are thousands of aircraft flying around the world today, things happen. Something has happened here and we cannot speculate any more about what did happen," Dixon said.

Passengers on Flight QF 30, enroute to Melbourne from London, had just been served a meal after a stopover in Hong Kong when they heard a loud bang, then their ears popped as air rushed out the hole.

After disembarking, they saw a gaping 9-foot wide hole at the joint where the front of the right wing attaches to the plane. Luggage from the cargo hold strained against the webbing used to keep it from shifting during a flight.

The passengers boarded another Qantas plane to Melbourne before midnight Friday.

An official of the U.S. Transportation Security Administration said initial reports indicated no link to terrorism.

Peter Gibson, spokesman for Australia's Civil Aviation Safety Authority, said speculation that rust contributed to the accident could be discounted.

"It's clearly an extremely rare and unusual event that a hole opens up in the fuselage," he told reporters in Australia. "I know there's a number of theories around, but they're just that at this stage, they're just theories. We don't have the solid facts."

Quoting pilot John Francis Bartels, the Manila International Airport Authority, said an initial investigation showed the aircraft suffered from "explosive decompression."

Boeing spokeswoman Liz Verdier said it was too soon to determine what caused the hole, but the company was providing technical assistance as part of an investigation led by the National Transportation Safety Board.

Verdier said the company was sending an investigator and three engineers to help in the probe.

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Associated Press writer Tanalee Smith in Sydney, Australia, contributed to this report.