Leah Yeager, a senior air safety investigator with the NTSB, said late Thursday investigators will enter the Flight Safety Building at Wichita Mid-Continent Airport after it's deemed structurally sound.
Heavy equipment will arrive today to remove portions of the building, Wichita Fire Chief Ronald Blackwell told The Associated Press.
The twin-engine Beechcraft lost power in one of its engines during takeoff Thursday morning before crashing into the building, according to the Federal Aviation Administration. Its pilot, Mark Goldstein, a former air traffic controller, died.
"I need to declare an emergency. We just lost the left engine," Goldstein told air traffic controllers before the crash.
The three others killed, who were in the building, haven't been identified. Five people were hospitalized, including one person in serious condition. Goldstein was flying solo.
About 100 people were inside the building, which houses Cessna Citation Jet Simulators, when the plane crashed.
"We were on a conference call and the building just kind of shook and rumbled," said Ryan Peterman, who works inside the building. "We saw the fuselage of the aircraft on top of the building on fire."
"I knew the air traffic control people would know if it was him and sure enough, they knew his voice," said Ron Ryan, a friend of Goldstein.
A 2005 bio provided to ABC News described Goldstein as someone who has “an extensive background in aviation and is considered to be a conscientious controller.” He also volunteered as a youth hockey coach.
ABC News' Matt Hosford, Meghan Keneally and The Associated Press contributed to this report.
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