The National Transportation Safety Board is investigating what caused a two-foot hole to open up in the fuselage of an American Airlines jet during a flight from Miami to Boston this week, giving passengers a scare, The Wall Street Journal reported on its website Thursday night.

The hold led to rapid decompression at 31,000 feet about 30 minutes into the flight, and oxygen masks were automatically deployed, the Journal said. The twin-engine Boeing 757-200, carrying 154 customers and a crew of six, descended to a lower altitude, turned around and landed safely at Miami International Airport.

"The crew declared an emergency and made a normal landing. There were no injuries," American Airlines said in a statement. "The aircraft has been taken out of service. The official cause of the loss of cabin pressure is unknown at this time."

After the landing, inspectors found a hole of about 1 foot by 2 feet just above the "A" of the American Airlines logo of the jet's front left cabin door, The Aviation Herald reported.

The incident has prompted Boeing Co. and federal air-safety officials to boost scrutiny of certain Boeing 757 aircraft, the Journal reported.

Industry officials told the Journal the incident bears some similarity to cracks found last month in the forward part of the fuselage of a United Airlines Boeing 757.

Boeing Co. is working on a service bulletin calling for stepped-up inspection of that portion of older 757 models, the Journal said.

A Boeing spokeswoman told the Journal the company is providing technical help to federal safety investigators and "will take appropriate action" as warranted.