A post-concert party at Booker T’s early Tuesday morning led to numerous fights, including one in which a concrete block was thrown through a car window.

Eric Lanier, 18, of Joliet is charged with aggravated assault, reckless conduct and disorderly conduct as one of many people who police say engaged in violence as the party let out at about 2 a.m., hours after a Nelly concert at Chick Evans Field House.

DeKalb police Lt. Jim Kayes said officers arrived at 1:30 to find several fights in progress. Soon, asphalt chunks from nearby construction projects were thrown both at people and through the window of a Cadillac Escalade.

Lanier, who allegedly threw the block at the car, is free on bond. The Cadillac’s owner has refused to press charges, and no other charges have been filed in the case.

“In my experience, if we were to find out what started the fight, it would be something that no rational person would think,” Kayes said.

About 10 DeKalb police officers, along with sheriff’s deputies and University Police, were needed to regain order. Kayes said fighters were sprayed with a refined version of Mace. Lanier reportedly tried to flee by hiding in a car, but officers eventually found him.

Tuesday’s outbreak has some remembering the night of Jan. 28, when three people were shot at a Regent Drive apartment after rapper Shyne performed at the Egyptian Theatre. No arrests were made in that incident, which is still under investigation.

In both cases, Kayes said, concertgoers were the ones committing the violence.

“We’re grateful that [Lanier] didn’t have a gun — otherwise we could have had a repeat of Jan. 28,” Kayes said.

Fliers on campus indicated a party at Booker T’s, 122 S. 1st St., but did not say who sponsored the party. Attempts to reach Booker T’s were unsuccessful Tuesday because of a disconnected phone line at the establishment.

Mike Brady, concert coordinator for Campus Activities Board, which sponsored Tuesday’s concert, said CAB had no association with the party.

Kayes added that not everyone who attended the rap concerts is to blame. He shared a theory by the late Chicago newspaper columnist Mike Royko.

“Five percent of any group, no matter who it is, will be jerks,” he said.