ST. PETERSBURG, Fla. (WFLA) – It's a "super pill" and it's invading the streets of Pinellas County. So far, it's killed nine people in a matter of weeks.

The lethal contents of this small, white pill are cleverly packaged. The pill looks just like a Xanax. But, looks can be deceiving. And, as it turns out, deadly. The fake Xanax is mixed with a powerful pain medication called Fentanyl, which is a highly addictive, strong pain medication commonly prescribed to cancer patients. The combination of Xanax and Fentanyl is so potent that it's killing people within minutes.

This first-of-its-kind tablet is a mystery for Pinellas County detectives and the Pinellas County medical examiner.

Pinellas County Sheriff Bob Gualtieri calls this a public health emergency. He has a message for the people in his county.

"You don't have to take a handful of them. All you gotta do is take one, and you're dead," Gualtieri said.

This dangerous new pill claimed the life of a 25-year-old woman in Dunedin over the weekend. The sheriff is working with other law enforcement agencies, including the St. Petersburg Police Department and the Clearwater Police Department, to warn people. "There's no other way to put it … You better stop buying this Xanax on the street because nine people are dead," he said Monday.

What's even scarier is that this super pill is so new its origin is unknown. No one knows who is making it, where it's coming from and why Pinellas County appears to be the only place it's found. Plus, it's super cheap – only $5 a pill.

Recently in Pinellas County, the biggest problem with people overdosing has been spice. Now, undercover cops are looking for this new pill.

Emergency room physician Dr. Raafat Hanna has been at Northside Hospital in Pinellas County for 18 years. Hanna describes the strength of Fentanyl. "It's 80 to 100 times as strong as morphine and about 40 to 50 times more times as strong as street heroin," he explained. "It's easy to get overdosed on a very small dose."

For now, investigators and police are keeping their eyes out for this pill on the streets. The sheriff is concerned about spring breakers coming to Florida and possibly buying this, but he adds, this crosses all boundaries.