PALM BAY, Fla. -- A Palm Bay sixth grader was arrested and three others are being investigated for allegedly dealing drugs at Discovery Elementary School. There are also allegations of an exchange of sex for drugs involving one of the students.

Because they are minors and only one faces misdemeanor charges so far, none of their names have been released. But once police caught one student, they too were stunned at what the young students were allegedly doing.

Four sixth graders from Discovery Elementary are being investigated for their roles in bringing marijuana from Miami to Palm Bay.

Thursday, police said they arrested a 12-year-old boy walking home from school after they got a tip he was trying to sell dime bags on the elementary school campus earlier in the day. Police believe his drug cache passed through the hands of three other youngsters, including a 12-year-old girl.

Investigators are looking into claims the girl obtained the drugs in exchange for sex while in south Florida over Christmas break.

"We were kind of shocked that it went this deep and this many people were involved, so we are taking it very seriously," Officer Neal Valenti said.

Police have only been able to recover two bags of marijuana. They have been told there were at least four. They don't know if there is more floating around.

Police believe they shut down the grade-school operation within a week of it starting up. All of the students involved have been suspended and all of them face expulsion from the A-rated school.

Police said two of the kids involved come from broken homes and have mothers who are in prison.