The city of Louisville, Kentucky, has experienced a spike in heroin overdose cases.

Louisville Metro Emergency Services received “52 overdose calls between midnight Wednesday and 8 a.m. ET Friday,” a jump from the 25 calls received in the same time frame last week, CNN reported.

Louisville Metro Emergency Services spokesman Mitchell Burmeister said most of the overdose calls were from heroin, although he also mentioned there were calls about “overdoses from alcohol, prescription medications and other controlled substances.”

“No overdose deaths were reported,” but one heroin user was a passenger who died in a car crash where the driver was also a heroin user.

There were 695 overdose reports in January 2017, “a 33 percent increase from last year,” the Courier-Journal reported.

Dr. Robert Couch, emergency medical director at Norton Audubon Hospital in Louisville, said that “doctors saw several overdoses during the 32-hour spike” and administered naloxone, a heroin antidote also known as Narcan.

Couch said that a growing number of overdose patients have to be admitted to the hospital after they’ve been revived because they experienced complications from the overdose.

The spike in overdoses all over the nation is blamed on heroin and the pain reliever drug fentanyl. Death rates from fentanyl and other synthetic opioids increased 72.2 percent from 2014-2015, according to the CDC.

“What generally is going on when you see this is someone has introduced a batch of fentanyl in the illicit drug supply that hasn’t been cut sufficiently,” said Van Ingram, Executive Director of the Kentucky Office of Drug Control Policy. “I’m afraid it’s a reality we’re going to see repeated far too often.”