Local and federal agents were carting away what was described as a huge cache of explosives from the apartment of the 21-year-old student who blew himself up outside the stadium where 84,000 watched a Sooners football game.

Joel Henry Hinrichs III, 21, a junior from Colorado Springs, Colo., died in the explosion, according to FBI officials.

Investigators believe Hinrichs detonated a bomb about 8 p.m. Saturday, just 100 yards away from the packed football stadium.

Police were overheard telling residents it would take "several trips and could take up to 24 hours" to remove it all, according to the Daily Oklahoman.

A canister trailer used for detonating or transporting potentially explosive material was being used to haul items away.

Officials said Hinrichs' motive for blowing himself up Saturday near the Gaylord Family - Oklahoma Memorial Stadium during the second quarter of OU's game against Kansas State remains under investigation.

OU President David Boren said Hinrichs was a student "who had very, serious personal problems that led to this tragic death."

Because of what happened, Boren said, the FBI had taken over the investigation.

Boren said the student had explosives strapped to his body.

Investigators would not say whether they believe Hinrichs intended to go inside the stadium before the detonation happened.

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