Six students from Harmony Science Academy were taken to area hospitals Thursday afternoon after ingesting the opiate hydrocodone, San Antonio fire officials said.
San Antonio fire spokeswoman Deborah Foster said the students are all in the sixth to eighth grades.
Harmony Science Academy, a charter school that serves kindergarten through 12th grades, is in the 8500 block of Lakeside Parkway.
The incident was reported around 2 p.m. Three ambulances responded to the school to treat the students, however school officials have yet to release any details as to what prompted the Fire Department to respond.
Foster said all students treated are OK and in stable condition.
Some parents said they were frustrated because school workers couldn't explain why ambulances were at the school when they came to pick up their children.
Parent Lucinda Crawford said she was shocked to see all the emergency vehicles parked outside.
"The children are very academically oriented here, it's not really what you expect," she said. "I have two kids here. They are good kids. The kids here are very well-behaved, well-mannered. They're more academically inclined. (The school) really pushes math, sciences, and college on these kids, so it's really a surprise to hear that."
Side effects of hydrocodone range from nausea, vomiting, constipation, drowsiness, dizziness or lightheadedness. More severe affects include slowed or irregular breathing or tightness of breath.
School officials have yet to make an official comment. They said they need to contact their central office in Houston before they can release any information.