Police in a small city on the U.S.-Mexico border say three students were arrested Wednesday for possessing fentanyl pills on campus, including one who had over 3,000 pills with her.

San Luis, Arizona, police say 18-year-old Noemi Hernandez-Madrigal had three plastic bags with over 3,200 blue fentanyl pills on her. The pills have an estimated street value of up to $48,000.

Hernandez-Madrigal and the other student, Alessandra Cardenas-Hernandez, 18, face several drug charges and are being held without bond. A 16-year-old boy who was also arrested hasn't been identified because he's underage. The students did not have attorneys listed for them who could comment on their behalf.

Lt. Marco Santana said police believe Hernandez-Madrigal intended to sell the synthetic drug that is gaining popularity as an alternative to other opioids, like heroin. Pills sell for about $10 to $15 each.

The opioid crisis has gripped communities across the U.S.

Exactly two years before the students' arrests, Arizona Gov. Doug Ducey signed an emergency declaration to address a growing number of fatal overdoses. The state instituted a number of measures, including training officers around the state to use a powerful spray that helps prevent death in people who are overdosing and new rules mandating how opioids can be prescribed.

In San Luis, a largely Hispanic city of about 33,000 people that draws thousands of farmworkers to work the nearby fields, officials have spent the past year waging a campaign against opioids. Border authorities said they arrested a 16-year-old American boy at the border in September for trying to sneak dozens of fentanyl pills into the country by wrapping them around his legs.

"We happen to be a border city, so (we're) on the front lines. It's gonna be smuggled through our city," Santana said. "But the main thing here is that we continue to combat that opiate issue that we have, not just here."

Santana said his department has on-campus officers at all the schools and that all officers carry Narcan, the brand name for naloxone, an antidote to opioid overdoses.

School nurses in San Luis also have the drug on hand, said Eric Patten, a spokesman for the students' school district, Yuma Union High School District #70.

Many schools around the country do this, and some states even mandate it.

"The arrests were certainly concerning for the district. As educators, you never want to see young people resort to that type of life-altering, negative decision," Patten said.