University of Oklahoma President David Boren on Tuesday said investigators are saying there is no known threat connected to the Saturday bomb explosion near a packed football stadium, and an FBI press release repeated Boren’s opinion.

OU engineering student Joel Henry Hinrichs III died when an explosive near or on him detonated as he sat on a bench outside George Lynn Cross Hall, the botany/microbiology building, on the South Oval. About 100 yards to the east was Gaylord Family-Oklahoma Memorial Stadium, where more than 84,000 people were watching the OU-Kansas State football game.

“While it would be premature to comment on the specifics of the current investigation or draw any final conclusions before the investigation is completed,” the release said, “the following is provided … as to facts relevant to public safety.”

The FBI release continued by stating, “There is no known current threat posed by any additional explosive materials. At this time, there is no known threat from any other person(s) related to this incident. At this time, there is no known link between Hinrichs and any terrorist or extremist organization(s) or activities.”

The FBI has not announced details about the bomb, but Channel 5 News reported Tuesday night that Hinrichs’ bomb contained acetone peroxide, or TATP. The highly unstable chemical can be made from household items, but it is very sensitive to heat and shock.

Law enforcement found more bomb-making materials Sunday at Hinrichs’ residence at the Parkview Apartments, and they were detonated that evening. Earlier last week, Hinrichs tried to buy ammonium nitrate fertilizer from Ellison Feed and Seed in east Norman.

Dustin Ellison said the student visited his store on Wednesday and asked to buy the fertilizing ingredient often used in bombs. Ellison said Hinrichs didn’t know how much he needed, and the store operator asked why the fertilizer was needed. After further discussion, Ellison said “something didn’t feel right” and decided not to sell any materials to him.

Hinrichs, 21, was a National Merit scholar from Colorado Springs, Colo. Boren said Hinrichs did not participate in a pregame recognition of freshmen National Merit scholars because he was not a freshman.

“Was he in the stadium, did he attempt to enter the stadium?” Boren asked rhetorically. “To our knowledge, at this point, the answer to that question is no.”

While saying it appears no one else is connected to the bombing, Boren made a shift in describing Hinrich’s death by saying, “I do not say suicide, I say it’s an individual death that we’re dealing with. That’s all we really know.”

Boren gave an overview of security measures OU takes for football games, a plan he said was developed shortly after the 9/11 attacks. OU uses bomb-detecting dogs and equipment to thoroughly check the stadium and surrounding areas for bombs and places many law enforcement officers throughout the stadium.

The precautions won’t change, Boren said he will suspend passouts, items given at certain gates during halftime that allow people to leave and re-enter the stadium. In addition, bag searches will intensify.

“We are going to ask our people to make an even more thorough search, be very careful to look down into those purses, bags, backpacks — anything being brought into the stadium that causes any suspicion,” Boren said. “This may mean our fans will have a little more inconvenience, and I urge fans to come a little bit earlier because they can expect their bags to be searched a little more thoroughly, also their cars entering the stadium garage.”

OU’s next home football game will be Oct. 22 against Baylor.

Norman and OU police and the Joint Terrorism Task Force are helping the FBI in its ongoing investigation.