One person is dead of a suspected fentanyl overdose in Gloucester Friday night.
Four others were given medical treatment in the same incident, say Gloucester police.
Police Chief John McCarthy warns that the strain of fentanyl suspected in the recent overdoses may be especially potent and dangerous to users.
"With this many ODs in that short a period of time, it appears that there's a strong source of drugs that came into the city sometime yesterday," McCarthy said Saturday morning. "Anyone using drugs should be aware it. Obviously something with great strength has come into the city."
A 2016 report by the DEA states that fentanyl is extremely lethal in a small dose. Just two milligrams could be fatal.
Gloucester police are conducting an investigation. So far, no arrests have been made.