Gunfire on the Texas Southern University campus wounded six people and scattered the crowd at a community rally, and police were investigating Thursday whether a gang rivalry was behind the drive-by shooting.

People were gathered Wednesday night at the event that included a Houston rapper's performance when a car drove by and shots sprayed out from the vehicle, school spokeswoman Eva Pickens said, citing witness statements to police.

The sound of gunfire made people drop to the pavement of the parking lot where the rally was being held to promote community service and voter registration.

Peter Role, a local music promoter, told the Houston Chronicle he heard what sounded "like the Fourth of July."

"We heard some gunshots and everybody was hitting the ground," Role said.

Six people, including one male student, were being treated for injuries that were serious but not life-threatening, Pickens said.

Campus police believe the violence resulted from a rivalry between two gangs, one from Missouri City, a suburb southwest of Houston, and the other from Fresno, a small town outside Missouri City, she said.

Before the violence, Houston City Councilman Peter Brown and U.S. Rep. Sheila Jackson Lee made appearances at the event billed as a "family block party," and local rapper Trae the Truth performed songs.

Lucinda Guinn, who's managing Brown's run for mayor in November's election, said she had no details on the shootings, but was dismayed that "an effort for bringing a very positive message to the community" would end in violence.

The rapper's publicist told the Chronicle that he'd left before the shootings.

An e-mail sent to Lee wasn't immediately returned. Her telephone mailbox was full and wouldn't take messages.

Texas Southern is a historically black university in Houston with an enrollment of around 10,000 students.

Click here for coverage from MyFOXHouston.com.