CUMMING, Ga. -- Officials at South Forsyth High School said three students overdosed during school Friday on a possible mixture of cough syrup and another drug.

"It's startling, we didn't know what was going on," said student Ashley Rivers.

The school went on lockdown Friday afternoon as EMS workers remained on standby in case other students became ill.

"We've had medical (issues) here before, but nothing this serious," Rivers said.

Sheriff's department detectives interviewed several teens after the overdoses and arrested two female students. The sheriff's office could not provide details about their charges.

Sheriff's department spokesperson Jennifer Caracciolo said school officials are unaware of any previous cases of substance abuse on school property.

"We're always trying to lookout for student safety and we have a huge campus at that school. But it's a continuous effort. We're growing fast nd new things that come out everyday that could be harmful to students," Caracciolo said.

"What do you do to make sure this doesn't happen again?" CBS 46 reporter Joanna Massee asked Caracciolo.

"Unfortunately, it's something we cannot guarantee doesn't happen again. Students can bring things to our campus," Caracciolo said. She said the school works to educate parents about drug abuse.

Laurie Thwaits has a sophomore and a junior. She feels for the parents of the students involved.

"You talk and talk and talk to your kids and you pray that they make the right choices," Thwaits said.