Story highlights Eight people are believed to have died from a lethal strain of heroin

The strain has been dubbed "Hollywood" heroin by police

(CNN) In one week, eight people are believed to have died from a lethal strain of heroin, Massachusetts State Police said.

The strain has been dubbed "Hollywood" heroin by police because it's branded with that name. It's not clear how long it has been in the state, Massachusetts State Police Trooper Dustin Fitch said.

The deaths were concentrated in the small cities of Holyoke and Chicopee, and there was one death in Springfield. Police departments have distributed warnings to the public about the drug.

Police are still investigating what makes this drug so dangerous. There could be a deadly mixture of additional chemicals in the batch, Holyoke Police Department Lt. Jim Albert said, or it could be so pure that even some addicts' bodies can't handle it.

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In Holyoke, at least two of the overdoses were fatal and another death is under investigation for links to the drug. A few people were able to be saved by using Naloxone , Albert said, and others were revived without it.

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