CHARLOTTE, N.C. -- A Charlotte-Mecklenburg middle school has banned students from wearing solid color T-shirts.

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VIDEO: School officials, parents concerned about possible gang connection involving T-shirts

The principal at Northridge Middle School sent a letter to parents on Thursday saying that groups of students have begun wearing white and pink T-shirts that could be a system to identify different gangs.

"We're not saying there are gangs at the school, but we are saying there had been some rumors and there were some students who were concerned and some discussions about not coming to school because they didn't feel safe," said CMS spokeswoman Jerri Haigler.

CMS brought in extra police and extra campus security officers to ease concerns.

Students were checked for solid color T-shirts as they entered the building and officials say they found several students in violation of the policy.

The students were given a school T-shirt to wear in class.

Two other schools, West Mecklenburg High School and Olympic High School, implemented similar gang clothing bans at the beginning of the school year.

School officials say the T-shirt ban will stay in effect indefinitely.