Synthetic marijuana is to blame for the majority of close to 75 overdose patients this weekend in Lancaster County, according to the county's largest emergency services provider.

Lancaster EMS responded to 65 overdose calls between Friday and Monday morning, according to executive director Bob May.

"In 72 hours, that's a lot of overdoses. And it's not heroin. We are dealing with K2 or synthetic marijuana," May said Monday.

None of the weekend overdoses was fatal, Lancaster County Coroner Dr. Stephen Diamantoni said.

Most of the overdose calls were concentrated in Lancaster city, but Lancaster EMS serves 17 other municipalities in the county, he said. The county has 60 municipalities in total.

“The point is, if we had over 70 overdoses (in our coverage area), there's more than that in the entire county,” May said.

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The Lancaster County District Attorney's office noted the spike in overdoses in a press release Monday.

Synthetic marijuana is an illegal manufactured chemical. Ingesting the substance can cause a person to hallucinate and act erratic and aggressive, according to the district attorney's office.

“While we are in the midst of a still-escalating opioid abuse epidemic, we must not forget the many other poisons being dealt and used in our communities,” District Attorney Craig Stedman said in a statement.

May said that the heroin antidote Narcan doesn't treat synthetic marijuana overdoses.

Synthetic marijuana can also raise blood pressure and cause reduced blood supply to the heart, as well as kidney damage and seizures, according to the National Institute on Drug Abuse.