SHARM EL-SHEIK, Egypt — The crash of a Boeing 737 packed with French tourists apparently was caused by mechanical trouble, not terrorism, French and Egyptian officials said Saturday.

The airliner, owned by Egyptian-based Flash Airlines, plummeted into the Red Sea off this beach resort, killing all 148 people on board. It had just taken off at 5 a.m. when the pilot apparently tried to turn back abruptly and the plane pitched into the deep, shark-infested Strait of Tiran.

Except for one Japanese, one Moroccan and 13 Egyptian crew members, all the people on board were French, authorities said.

The cause of the crash remained a mystery Saturday night as searchers hunted the waters for the flight data and voice recorders. The crew didn’t put out a distress call, airport officials said, and other planes took off and landed smoothly on the clear morning in this sun-washed tip of the Sinai Desert.

The aircraft simply vanished from the radar a few minutes after taking flight. "There was a problem at takeoff," France’s deputy transportation minister, Dominique Bussereau, said at Paris’ Charles de Gaulle airport. "It tried to turn back and … it crashed."

Egyptian and French officials were quick to emphasize that there was no reason to suspect that the plane had been attacked, and France wasn’t expected to open a counterterrorism probe. The crash "is absolutely not the result of a terror act, but is linked to a technical failure of the plane," Egyptian Foreign Minister Ahmad Maher said,

Radar images indicate that the plane took flight and turned left as normal, then suddenly straightened out, turned right and tumbled into the sea. The last communication with the plane was at 5,300 feet.

On Saturday, sodden suitcases and body parts bobbed in the water a few miles from shore, along with shoes, life preservers and shards of the plane. The jet fell into the water between Egypt and Saudi Arabia over a deep underwater crevice thick with sharks.

Flash Airlines, which has been in business for six years, said the Boeing 737 was one of two it owned.

A Venice airport official said the plane had undergone recent mechanical and safety checks in Italy, and nothing abnormal was noted.

A Boeing investigator is en route to join the U.S. National Transportation Safety Board and the U.S. Federal Aviation Administration to support the investigation, which is being led by Egyptian authorities, Boeing reported on its Web site. The airplane, a 737-300, was delivered in October 1992, Boeing said.