Fentanyl was to blame, city officials said.
Responders administered Narcan to five women in all -- ages 29 to 41 -- and conducted CPR on the most seriously injured victim, who'd apparently staggered toward the middle of the lot before collapsing.
She remained unresponsive despite efforts to revive her -- first by passersby who include a nurse practitioner, then by police and EMS, witnesses told Daily Voice.
She was in serious but stable condition at Hackensack University Medical Center, responders said.
Two of the victims quickly came around but still weren't fully conscious, said an employee of a nearby business who was among those who initially rushed over to help shortly before 5:30 p.m. March 15.
The fifth woman was "clearly very high" and trying to revive the most seriously injured one when she was pulled away by responders, he said.
Witnesses said all work at a restaurant in the mall, which is more commonly known as Riverside Square, just off Route 4.
Street heroin and cocaine are often laced with fentanyl, a synthetic drug that authorities say is responsible for most overdose deaths -- and can kill even in the smallest amounts.“The scourge of illicit drugs is magnified exponentially when fentanyl is introduced," Hackensack Police Director Raymond Guidetti said. "Lacing drugs with fentanyl increases the profit margins for those distributing illicit drugs, while dramatically increasing the deadly risks to those who come in contact with it."
City police and the Bergen County Prosecutor's Office were investigating the source of the drugs, assisted by the Bergen County Sheriff's Office, which collected evidence.
“I want to assure the community that we are already in the process of thoroughly investigating this matter to find the source of this dangerous substance, and will do everything within our power to prosecute those responsible to the fullest extent of the law,” said Hackensack Police Capt. Michael Antista, the officer in charge of the department.
“I want to thank the great men and women of the Hackensack Police Department for their swift response and once again proving their expertise in times of crisis," the captain said.
Some of the women had apparently been in an SUV about 50 feet from a business entrance and at least one other in a vehicle parked nearby, a witness told Daily Voice.
"It's in the area where people go to get high," he said.
Police cordoned off the area with yellow crime-scene tape.
The SUV's doors were open and three $20 bills still could be seen lumped on the front seat.
“It is truly heartbreaking to see the terrible toll taken by these illicit and dangerous substances,” Hackensack Mayor John Labrosse said in a statement.
The mayor said his office "will continue to offer any necessary support to the emergency responders and the rest of the community as the situation continues to unfold.”
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