Investigators sifted through debris inside a luxury high-rise apartment Thursday for clues to why a small airplane carrying New York Yankees pitcher Cory Lidle slammed into the building, killing the pitcher and a flight instructor.

National Transportation Safety Board member Debbie Hersman said investigators found debris scattered everywhere.

Aircraft parts and headsets were on the ground. The propeller broke apart from the engine, which landed on the floor of an apartment. The bodies fell to the street. On Thursday, Police Commissioner Raymond Kelly identified the flight instructor as Tyler Stanger of Walnut, Calif.

Photo Essay: New York City Plane Crash

Residents were allowed back into their apartments except for the 39th through 41st floors, where rooms were gutted by the fire and a six-story scorch mark marred the red brick.

"There's a significant amount of damage," Hersman told a cable news station Thursday morning.

She said investigators were taking fuel samples, looking at maintenance records and examining Lidle's flight log book — "anything that will give us a clue about what happened."

Lidle talked often of his love of flying, describing it his escape from the stress of professional baseball and a way to see the world in a different light.

"No matter what's going on in your life, when you get up in that plane, everything's gone," Lidle told an interviewer with Comcast SportsNet in Philadelphia while flying his plane in April.

Lidle and Stanger boarded the same single-engine plane Wednesday afternoon for what was supposed to be a leisurely flight around New York City. They took off from a suburban New Jersey airport, circled the Statue of Liberty and flew past lower Manhattan and north along the East River.

Video: NTSB 'Still Gathering Facts on NYC Plane Crash

Video: Yankees Announcer Reacts to Cory Lidle's Death

Twenty minutes into the flight and just moments after passing the 59th Street Bridge, the plane smashed into the Upper East Side condominium building, killing the two men and briefly raising fears of another terrorist attack in this scarred city.

"It was very scary," said Diane Tarantini, who was sitting in an outdoor courtyard when she heard a boom and saw a fireball across the street. "It brings back all these memories about planes hitting buildings, the terror of that day in September."

The plane slammed into apartments that were 30 and 31 stories above the street, though the floors are numbered at 40 and 41. The building is about 40 stories high.

Firefighters put out the raging fire in less than an hour. Twenty-three people, mostly firefighters, were taken to hospitals, but all had been released by Thursday except Ilana Benhuri, who was in fair condition, said John Rogers, spokesman for New York Presbyterian Hospital/Weill Cornell Medical Center.

Benhuri's husband, Dr. Parviz Benhuri, said his wife was home when the plane hit their window, breaking the glass and spewing flames. She suffered burns on her back and legs but was in good spirits, he said.

"She ran fast. That was a miracle. I don't know how she made it," he said. His brother, Dr. Marc Benhuri, said her housekeeper helped her escape.

Lidle's passport was found on the street, according to a federal official, speaking to The Associated Press on condition of anonymity. It was not clear who was at the controls.

Hersman said the FAA was reviewing aircraft-control tapes at the NTSB's request, and so far had no indication of a mayday call.

The Cirrus SR20 was built in 2002 and purchased earlier this year, she said. It was registered to Lidle. The four-seater is equipped with a parachute in case of a mishap, but it apparently was not used.

NTSB records indicate 12 accidents involving the Cirrus SR20, first flown as a prototype in 1995. In two accidents this year, pilots reported engines losing power.

Lidle had repeatedly assured reporters in recent weeks that flying was safe and that the Yankees — who were traumatized in 1979 when catcher Thurman Munson was killed in the crash of a plane he was piloting — had no reason to worry.

His teammates were stunned at the crash. Jason Giambi, who played high school baseball with Lidle and knew his family, said in a statement: "We were excited to be reunited in New York this year and I am just devastated to hear this news."

On Sunday, the day after the Yankees were eliminated from the playoffs, Lidle cleaned out his locker at Yankee Stadium and said he planned to fly to California, making a few stops. Lidle had reserved a room for Wednesday night at the historic Union Station hotel in Nashville, Tenn., hotel spokeswoman Melanie Fly said.

Family and friends converged on Lidle's home in the Los Angeles suburb of Glendora, Calif.

Lidle's twin brother, Kevin, said in a cable news interview that the family was having a tough time.

"But what can you do? Somehow you hang in there and you get through it," he said. "I've had a lot of calls from friends and family, people calling and crying. And they've released some emotions, and I haven't done that yet. I don't know — I guess I'm in some kind of state of shock."

Lidle began his career in 1997 with the Mets and also pitched for Philadelphia, Tampa Bay, Oakland, Toronto and Cincinnati.

Stanger, the flight instructor, operated a flight school in La Verne, Calif., and lived nearby with his wife and young child.

The military scrambled fighter jets over New York and other major cities immediately after the crash. Adm. Timothy Keating, commander of U.S. Northern Command, told The Associated Press military officials knew it likely wasn't a terrorist act "about a half an hour after it happened."