CAMDEN Even in a city where emergency responders are used to dealing with drug crises - Camden averages one nonfatal heroin overdose a day - there was alarm when there were a dozen in just one hour Tuesday, beginning at noon.

"It wasn't just the number of overdoses, but the speed at which they came in," said Kenneth Szwak, director of Emergency Medical Services at Our Lady of Lourdes Medical Center.

The patients - 15 eventually, all but one suburbanites - were treated at Cooper University Hospital, Virtua's Camden and Berlin branches, or Lourdes. All were released by Wednesday.

Camden County police and emergency responders blamed the spike on a particularly bad batch of the drug. Police were reluctant to release concrete information about the strain - labeled "Magic" by street peddlers - to discourage abusers from seeking out the dangerously potent batch.

Though the frequency of overdoses in Camden County has steadily increased over the last few years, a spike like this in a single day is an anomaly, Police Chief Scott Thomson said Wednesday.

In addition to recording one nonfatal overdose each day, Thomson added, Camden City averages a heroin-related fatality every 10 days.

On Tuesday, 11 of the calls came in from Camden, and the remaining four from Gloucester City, Berlin, and Stratford.

Fourteen of the patients hailed from South Jersey suburbs, Thomson said. That underscored concerns expressed recently by addiction experts that heroin abuse is not confined to conceived problem areas like Camden.

Szwak, off-duty during the surge, was unable to put his finger on what made this batch so potent.

"Batches vary in the degree to which [they] affect a person," he explained. "This one influenced users quickly and deeply."

Initial tests conducted by Camden County police indicated that the batch was not cut, or mixed, with fentanyl, a synthetic opioid that can stop breathing when administered improperly, but the testing had yet to determine the reason for the users' reaction to the batch.

Heroin abuse is on the rise at both the national and state levels, John D. Pellicane, director of the Camden County Department of Health and Human Services, said Wednesday.

Pellicane said that from 2009 to 2012, the number of heroin-related deaths jumped from around 97 to 138 in the county. There were 112 heroin-related fatalities in Ocean County in 2013, up from 53 the year before. Health officials in Burlington and Gloucester Counties could not be reached.

John Thompson, director of the Living Proof Recovery Center in Voorhees, blamed the spike on young adults' gaining access to opiate painkillers at increasingly younger ages.

"Not every person with a predisposition to using drugs knows they have it," Thompson said. "The drugs need to be monitored. It can't just be, 'You have a broken leg, put a cast on it, take a pill.' "

Thompson, who worked with homeless addicts at a recovery center in Camden last year, said that many users switch from painkillers to heroin out of cost concerns.

"Thirty milligrams of Percocet cost around $80," he said. "Either you can pay $80 per pill, or go pay $10 for some heroin, which will do the same thing but do more damage to your body."

On Wednesday, Assemblywoman Marlene Caride (D., Bergen) introduced legislation that would toughen the penalties for heroin possession.

"It's fortunate that everyone survived," said Jason Laughlin, spokesman for the Camden County Prosecutor's office. "They can tell [police] where they got it."

Contact Jerry Iannelli at 856-778-3882.