The bodies of nine people killed in the crash of a Turkish Airlines flight in the Netherlands have been formally identified, a Dutch mayor said Friday.

Theo Weterings of Haarlemmermeer said the five Turkish victims would be taken home as soon as further formalities and paperwork allow, while the U.S. Consulate was still deciding when to transport the bodies of the four Americans killed.

Of 135 people on the Boeing 737-800 that shattered into three pieces in a field shortly before it was due to land Wednesday morning, 63 remained hospitalized, one in critical condition, Weterings said.

As 40 investigators swarmed the crash site Friday, the plane's flight data and cockpit voice recordings were being analyzed in Paris. Sandra Groenendal, spokeswoman for the Dutch Safety Authority, said a first assessment of what went wrong according to the black box data would likely be released by Wednesday.

Turkish Airlines on Friday said the dead included pilots Hasan Tahsin Arisan, Olgay Ozgur and Murat Sezer and flight attendant Ulvi Murat Eskin.

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Boeing has confirmed that four of its employees were on the flight and released their names, but has not specified the two known of have died. A third was in critical condition Friday and the status of a fourth was not yet certain.

The company was flying their relatives to the Netherlands if they wanted to come, spokesman Andrew Davis said Friday, but he gave no details of their movements.

Flight TK1951 was coming in from Istanbul when it crashed about one mile short of the runway at Amsterdam's Schiphol Airport.

One survivor, Henk Heijloo, said the last message he heard from the captain was for flight crew to take their seats. He said it took him a while to realize the landing had gone wrong.

"We were coming in at an odd angle, and I felt the pilot give the plane more gas," he said. He thought the pilot might have been trying to abort the landing, because the nose came up.

Pieter van Vollenhoven, head of the Dutch agency investigating the crash, said Thursday that the plane had fallen almost directly from the sky, which pointed toward its engines having stopped. He said a reason for that had not yet been established.

Groenendal said engine failure was still only "one of the possible scenarios" for the crash. Other possible causes range from weather-related factors to insufficient fuel, loss of fuel, navigational errors, pilot fatigue or bird strikes.

"(It) just fell straight down and then you heard the engines at full power as if it was trying to go forwards," survivor Fred Gimpel told the Dutch NOS news.

Witnesses on the ground said the plane dropped from about 300 feet.

Several crash survivors returned to Istanbul on Thursday — including Kerem Uzel, a student. He told Turkey's NTV television that he didn't realize anything was wrong until the plane was skidding through the muddy field.

Turkish Airlines chief Temel Kotil said Arisan, the plane's captain, was an experienced former air force pilot.

The airline also denied reports that the plane, which was built in 2002, had had technical problems in the days before the accident. The plane underwent routine maintenance Feb. 19, and had to delay a flight Feb. 23 — the day before the crash — to replace a faulty caution light.