NORMAN, Okla. -- A University of Oklahoma student with "emotional difficulties" was identified Sunday as the person who was killed when an explosive attached to his body detonated near a packed football stadium, authorities said.

The remains of Joel Henry Hinrichs III, 21, were recovered after the explosion.

"We know that he has had what I would call emotional difficulties in the past. And as I said, this is an individual death. There is certainly no evidence at this point which points to any other kind of motivation other than his personal problems," OU President David Boren told reporters Sunday afternoon.

Boren declined to say where Hinrichs was from, but a student telephone book lists a permanent address in Colorado Springs, Colo. He said he didn't know whether a suicide note had been found.

Hinrichs' father, Joel Henry Hinrichs Jr., said he was very surprised to hear the news about his son.

"We exchanged e-mails on an irregular basis, several in the last month, and nothing seemed out the ordinary," the father told The Associated Press.

His son was a National Merit Scholar who graduated in May 2002 from Wasson High School in Colorado Springs and began attending OU in the fall of that year with a major in mechanical engineering.

"He was a very intelligent, very private individual who somehow lost the confidence that his life would be a good one," the elder Hinrichs said. "Obviously, every parent believes their son is a good kid, and I certainly believed that about mine."

Joel Henry Hinrichs Jr. said he had not figured out whether he would travel to Norman.

Besides his parents, Hinrichs was the youngest of five children -- three boys and two girls.

Authorities haven't identified what kind of explosive device was used.

The explosion occurred around 8 p.m. Saturday while he sat on a bench outside George Lynn Cross Hall, officials said.

Authorities cordoned off the area west of the stadium and no one was allowed to leave the facility immediately after the blast for security reasons. Spectators were allowed to go outside about 30 minutes later.

There were no other reports of injuries and Boren said football spectators were never in danger. More than 80,000 people were in the nearby stadium watching Oklahoma play Kansas State.

The game, which was in the second quarter at the time of the explosion, went on without interruption and no announcement was made until the final minutes of the game. At that point, spectators were only informed to avoid the traffic circle where the explosion occurred, but were not told why.

"We wanted to make sure that people were not surprised as they came out, but we didn't want to make the announcement too early because we didn't want to cause any kind of panic within the stadium because it was fully under control at that time and we were most worried about what would happen if people left the stadium," Boren said.

Other than some broken windows, the building sustained minor damage, Boren said. The area remained taped off Sunday as fire crews hosed down nearby sidewalks and three buses that were parked in front of the building.

Authorities found numerous explosive materials when they searched Hinrichs' apartment, The Oklahoman newspaper reported in today’s editions.

Police were overheard telling residents of the student apartment complex near the stadium that it would take "several trips and could take up to 24 hours" to remove the material, the newspaper reported.

City officials informed other nearby residents to evacuate, Boren said.

"Obviously we're not going to let them come back into the area unless we know it's safe, and we can't have people going back into the area if it might interfere with the investigation," he said. "They're going through everything with a fine-toothed comb."

Television news footage showed investigators retrieving items from a trash bin at the complex, which is located a couple of blocks east of the stadium.

Investigators have no information to suggest there is any additional threat posed by others related to the explosion, Hernandez said.

The Bureau of Alcohol, Tobacco, Firearms and Explosives, the Joint Terrorism Task Force, OU police, Norman police and the Cleveland County Sheriff's Office also are investigating the incident.

Boren said he expected the area to be opened on Monday and classes would be unaffected. Counseling will be made available to those who desire it, he said.

"My greatest concern was to make sure that all of our students were safe and that there is no ongoing threat to our students at the university, so that we could continue our classes as usual," Boren said.

Hinrichs' sister, Berkeley, said her brother may have been doing an experiment, and didn't mean to kill himself.