PHOENIX -- Five Cactus Shadows High School students face serious charges for selling prescription drugs on campus, Scottsdale police said late Friday.

The school said it started investigating the drug situation on Monday after a 16-year-old overdosed on the muscle-relaxer Soma and had to be rushed to the hospital.

Soma is the street name for the drug "carisoprodol." It is a narcotic muscle relaxant, similar to vicadin and can cause serious side effects, including coma and even death.

She told investigators that another student sold her the pills, officers said.

The school resource officer said the first student bought her pills from a 16-year-old boy.

"We learned that he'd bought 1000 pills down in Mexico the week prior," said Sgt. mark Clark of the Scottsdale Police Department. "He'd brought them up to the school and was selling them."

The student and four others were implicated in three different instances of drug use and selling on campus, officers said.

The students range in ages from 15 to 18-years-old. More than a thousand pills were brought into the school, according to police.

All the teens reportedly got the drugs in Mexico, officers said.

"Our biggest concern is to try to gather up the pills that were sold and are out there," Clark said. "We've only recovered less than half of the pills that we've been told are out there."

The five students were released to their parents.