University police say the problems began inside during the concert. After security officials escorted 10 to 15 people outside for fighting, it became a gun battle in the parking lot.
Fresno State Police say gang members carried their differences outside Thursday night when several shots were exchanged in the parking lot. Moments later, officers were questioning six people.
Fresno State Police Chief Dave Huerta said, "We don't know who the suspects are, we just have six detained."
Investigators found one gun, believed to be used in the shooting under a car. One person was arrested on a probation violation. But no one was arrested for the shooting.
Friday empty bottles of hard liquor still lingered in the parking lot. Some people who attended the concert also left their cars since the scene was roped off and processed for evidence long after the event was over.
The MMG Concert featured rapper Rick Ross and attracted a younger crowd. Officers say they were in lot three almost immediately after the violence began.
Several casings were found in the parking lot, but investigators did not say how many rounds were fired. One person was hit by a bullet, but does not have life threatening injuries.
Fresno State officials refused to answer any questions about whether any extra security measures were in place for the rap concert. They will also not address whether any stepped up security will be in place at future save mart center events.
