The stage rigging that collapsed and killed seven people at the Indiana State Fair last summer did not meet industry safety standards and the tragedy was compounded by the absence of a fully developed emergency plan, investigators concluded in reports released Thursday, likely adding weight to victims' legal claims.

During a 90-minute presentation to the Indiana State Fair Commission, officials from Thornton Tomasetti, an engineering company, and emergency planning advisers Witt Associates detailed the results of their separate investigations into the Aug. 13 collapse, which also injured dozens of people and which happened just before the country duo Sugarland was to perform.

Fair organizers were not legally required to have the stage inspected because it was a temporary structure, Thornton Tomasetti reported. But company vice president Scott Nacheman told the commission that the metal rigging structure used to support speakers and lighting didn't meet industry safety standards, which would require it to be able to withstand wind gusts of 68 mph.

Gusts reached an estimated 59 mph when the rigging collapsed, he said.

The company determined that parts of the rigging's support system began to give way at gusts of 33 mph and that by the time they reached 43 mph, the structure could no longer support itself. Testing showed gusts of 25 mph could have caused the structure to collapse.

"Once gravity had taken over there was essentially no way the structure could support itself," Nacheman said. "Gravity takes over and the structure fails."

The report says the stage structure had support wires attached to concrete barriers used as ballast to hold it in place, but that the system was inadequate to withstand lateral forces such as high winds and was "grossly inadequate."

The state hired Thornton Tomasetti to review the stage structure and Washington-based Witt Associates to investigate the fair's emergency plans and response.

Charlie Fisher, a vice president for Witt Associates, told the commission that "an ambiguity of authority" resulted in confusion and uncertainty over who was in charge of public safety as officials discussed whether to postpone the concert just before strong winds blew stage rigging onto waiting fans.

He said fair organizers' overall state of preparedness "was not adequate" for an event that size, their emergency response plan and procedures weren't fully developed, and they didn't utilize the plans they did have on the night of the collapse.

Kenneth Mallette, vice president of preparedness services at Witt Associates, said weather conditions had been a topic of discussion and analysis throughout the day. He said a fair representative asked Sugarland's tour manager to delay the start of the show, but the band resisted, its tour manager saying, "It's only rain. We can play."

About 20 minutes later, State police Capt. Brad Weaver, who was backstage, expressed concerns about the approaching weather and urged fair Executive Director Cindy Hoye to shut down the concert minutes before the collapse, Mallette said.

"We need to call this. We need to call this off," Weaver told Hoye, according to Mallette.

Hoye nodded in agreement, but by the time they were heading to the stage to cancel the show, the rigging collapsed, Mallette said.

Witt Associates' report said that at 8:39 p.m., about 10 minutes before the concert's scheduled start, the National Weather Service issued a severe thunderstorm warning for the area, but that neither Hoye nor Weaver received that information.

Fair commission Chairman Andre Lacy said Hoye had offered to resign but that he asked her to stay on in her position. He said the fair's leadership has much to learn and improve upon but stressed that the investigations weren't meant to assign blame for the collapse.

"We put ourselves willingly and openly — and publicly — under the microscope so that we could learn all that we can and apply that learning to avoid a tragedy like Aug. 13 from ever happening again," Lacy said.

Hoye said the findings couldn't change the past but that she hopes will serve as a model for other fairs in Indiana and elsewhere.

"Hindsight is an incredible teacher, and that's all we have right now," she said.

At the end of its meeting, the fair commission voted to begin implementing both reports' recommendations and to hire a chief operations officer to oversee the process and handle public safety at the fairgrounds, which are about five miles north of downtown Indianapolis.

Gov. Mitch Daniels said the state would share the reports' findings "with any state who will listen." Those discussions will begin with a meeting on national safety standards for outdoor temporary stages and structures scheduled later this month in Indianapolis.

"We'd give anything to have that night over, but occasionally something positive can come out of terrible tragedy, and we have to do all we can to make that happen here," Daniels said.

Thursday's findings are expected to provide key information for several lawsuits filed against Sugarland and companies involved with building the stage. Singer Jennifer Nettles was schedule to give a deposition Thursday in West Virginia, and fellow band member Kristian Bush was to testify Friday.

The duo issued a statement Thursday through spokesman Allan Mayer in which they said "no one who wants to get to the bottom of what happened more than we do."

"We want all the facts to come out, not only for the sake of all the victims and their loved ones, but also so we can make sure that nothing like this ever happens again," they said.