YORK COUNTY, S.C. --  Experts say heroine use in Charlotte and the surrounding areas is on the rise. Drug investigators in York County have seized thousands of dollars worth of black tar heroine and other varieties. The fear now is what could be mixed in with the opioids.

In a recent drug bust, authorities seized thousands of dollars worth of black tar heroin in balloons and what they call china white.

"We've seen an increase in heroine. Of all the drugs, including the cocaine, including the crack, we've seen more heroine right now then anything else,” said Marvin Brown, with the York County Multi-Jurisdictional Drug Enforcement Unit.

Brown said it’s a growing problem.

"We've had three overdoses in the last few weeks,” said Brown.

Drugs travel to York County from Charlotte and Greenville.

"We're caught in the cross fire," said Brown.

Officials with one treatment center in Charlotte, Absolute Advocacy, said they’ve noticed an increase in the number of people seeking treatment for heroin abuse.

"They've gotten off of heroine for a short while or they've been in jail for a short while. And when they come out they get back on it, and I guess they get back on the same dosage they were using before,” said Brown.

A major concern is what’s mixed with heroin. Last year in High Point, law enforcement saw a spike in Fentanyl, a narcotic pain reliever, mixed in with heroin.

"They all contained fentanyl in one concentration or another, along with a variety of other drugs. And the scariest one, one sample was all fentanyl. It wasn't even mixed with heroin, which our medical professionals here tell me that's a death sentence immediately,” said Chief Marty Sumner with High Point Police.

In York County, people aren’t waiting to mix that drug in.

"People take a knife or a razor and they cut the patches. They squeeze the fentanyl out of the patches or they actually suck on the patches,” said Brown.

As numbers increase, the goal is to stop the drug abuse by tracking the drug back to the beginning.

"We’ve been fairly successful tracing it back to the persons who sold the drugs to the people who actually died, and we have made charges,” said Brown.

The State Bureau of Investigations says heroin overdoses have increased about 300 percent in the past two years.