(CNN) -- The Indiana State Fair Commission is hiring New York-based engineering company Thornton Tomasetti Inc. to investigate Saturday's deadly stage collapse, officials said Tuesday.
Personnel from the company have already arrived on site and begun their investigation. They are expected to deliver a report with their findings and recommendations to the commission, which will make it public.
Thornton Tomasetti, founded in 1956, has worked on a variety of high-profile projects, including ones in the aftermath of the 2007 Interstate 35 bridge collapse in Minneapolis and the 9/11 attacks in New York City.
The company's investigation should run parallel to those being done by the Indiana State Police and the Indiana Occupational Safety and Health Administration, said Indiana State Fair Commission Chairman Andre Lacy.
"Our goal is to learn everything we can why this tragedy occurred. We won't leave any question unanswered, from both a structural standpoint and the decision that was made," he said. "We know that many are eager for answers today. We don't have them. And we won't speculate."
Lacy spoke to reporters at an afternoon press conference in Indianapolis, where officials fielded questions about what could have caused or contributed to the collapse.
The accident occurred shortly before the country music duo Sugarland was to take the stage before an audience of about 12,000 Saturday night. Five people were killed and at least 40 were injured.
Metal scaffolding fell onto the "Sugarpit," a section usually occupied by Sugarland's most ardent fans, just minutes after authorities took the stage to warn the crowd to seek shelter, according to a timeline of events released by investigators.
Indiana State Fair spokesman Andy Klotz said officials had made the decision to evacuate and that people were on their way to make the announcement when the storm hit.
Video of the accident shows blue canvas top fraying and flapping seconds before the steel scaffolding gave way, sending a heavy bank of stage lights and metal onto fans closest to the outdoor stage.
Forecasters had warned heavy rain and strong winds would hit the fair nearly two hours before the storm moved through Saturday. The National Weather Service estimated winds at 60 to 70 mph.
"We followed a protocol very directly. It was working. This was a freakish act of God and I don't know how it could have been prevented," Klotz said.