A student attending the Flowery Branch High School homecoming dance on Saturday night became ill when someone placed an unknown substance in her drink, and now school district officials and the Hall County Sheriff's Office (HCSO) are investigating to determine who is responsible.

Derreck Booth, spokesman for the Hall County Sheriff's Office, said the 15-year-old girl became ill after she drank a cup of lemonade at the dance.

"She reportedly got the drink in a hallway or a classroom, but she has no recollection of who gave her the drink or where she got it from," Booth said.

He said lemonade was being served in the concession area at the dance, but he said a review of surveillance footage from the dance didn't show anyone tampering with the beverage containers.

"In fact, the drink was in - from our understanding - a couple of large coolers or jugs, if you will, with sealed lids," Booth said. "The concession area was even monitored by teachers, chaperones for the whole evening, so nothing there."

Booth said the girl's date is not considered a suspect in the incident.

"Not at all, not at all," Booth said. In fact, he said the date and his mother followed the girl and her mother to the hospital emergency room and remained with them while doctors checked out the victim.

Booth said the girl is expected to make a full recovery, but whatever was in her drink made her very ill.

"She was suffering from symptoms including amnesia, headaches, some skin rashes and vomiting," Booth said.

For now, investigators continue to analyze the substance that was placed in the girl's drink.

"I think it would be fair to classify it as a suspected drug," Booth said.

The school system said it is taking the incident very seriously, offering a $1,000 reward for information that leads to the arrest of the person or persons responsible for spiking the drink.