Burlington police on Wednesday said that fentanyl, a potent synthetic painkiller that has caused scores of fatal drug overdoses, was found in heroin that caused three recent overdoses in the Queen City. 

The victims all survived, police said. Authorities used naloxone, a overdose-reversing drug that Burlington police carry, to save some of them, police said.

Fentanyl is impossible for users to detect. It has been showing up in batches of heroin in Vermont with increasing frequency, police said. It caused 29 fatal overdoses in the state in 2015, up from 18 in 2014, according to the Vermont Department of Health. 

Musician Prince fatally overdosed on fentanyl in April at his home in Minnesota.

"The presence of fentanyl in the Burlington heroin supply has been rising steadily based on information we have been getting from the addicted community and the Vermont Forensic Laboratory," Police Chief Brandon del Pozo said in a press release.