HOUSTON -- Houston could have a new crime wave in the wake of Hurricane Katrina brought in by New Orleans gangs, the FBI warned Wednesday.

The FBI intelligence memo obtained by KPRC Local 2 warned other law enforcement agencies that gang member evacuees might bring an "us versus them" mentality that could lead to shootings and other violence all over Houston.

On Tuesday, a group of Louisiana evacuees and students from a southeast Houston high school were involved in a fight, which escalated into a riot that closed school early.

"Yesterday took away the opportunity to pretend there was no problem," said Gayle Fallon, with the Houston Federation of Teachers.

Up to 25 students were involved in the 8 a.m. fight at Jesse Jones High School, located at 7414 St. Lo.

Fallon said the bloody brawl may be the first of many unless the troublemakers are removed to disciplinary schools.

"There are no second chances on this or we could see our schools out of control," Fallon said.

The FBI said gangs will emerge as a sense of security wherever evacuees gather. The memo said gangs would steal guns and set up new drug connections as they take hold of the turf of Houston gangs.

"They may not have specific colors. They may have tattoos, they may not," said Chuck Brawner, with the Spring Branch Independent School District.

Brawner said there have been no problems within Spring Branch ISD but his officers are watching for clashes with existing gang members or anything else that happens.

"On the other hand, they could bond together and become one unit, which would make it a larger population of gang members than we're used to seeing," Brawner said.

The FBI would not comment on the warning to police agencies. It listed the names of 15 gangs. Only one of those gangs wears colors to identify themselves, which officials said would make it more difficult to track.

Students at Jones High School had more police and security on hand when they arrived at class Wednesday morning.

Officials said Tuesday's brawl started when a student threw an unopened soda can at a group of evacuees, which was retaliation for a fight the day before.

Ministers were also at the campus to ease tensions.

"We want our citizens of Houston and our citizens from New Orleans to know that we've got to come together as one and we do that by communicating, by sharing," said James Nash, with Houston Ministers Against Crime.

Five students were arrested in the brawl. Three others were treated for minor injuries at area hospitals.