National Transportation Safety Board officials are reviewing the records of the pilot involved in a helicopter crash that killed all four people on board in Texas on Sunday.
The deadly crash killed four people, including a child, after the helicopter struck a radio tower and sparked a large fire in Houston on Sunday, officials said.
The helicopter, which was operating as an air tour flight, had taken off from Ellington Airport in Houston, the NTSB said. It was not equipped with a flight recorder or "black box."
"Our condolences go to the family and friends of those who were lost," NTSB investigator Brian Rutt said on Monday, adding the wreckage is a "complex scene" and officials are being meticulous in examining all the evidence available.
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As part of the crash investigation, NTSB officials are investigating the pilot, the aircraft and the operating environment, NBC affiliate KPRC-TV reported on Tuesday. NTSB officials also began recovering debris for further examination.
Officials are also gathering additional information such as the helicopter's maintenance records, flight track data as well as air traffic control communication recordings, surveillance videos and witness statements, KPRC reported.
The crash also damaged some vehicles on the ground but no people were reported injured, Houston police Lt. Jonathan French said.
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“This was a horrible tragedy, but obviously it could have been much worse,” French said on Monday.
The NTSB expects to release a preliminary report in 30 days.