PHILADELPHIA (WPIX) — Driving in Philadelphia’s embattled Kensington neighborhood on Tuesday to get a firsthand look at the effects of xylazine, an animal tranquilizer that was turning fentanyl addicts into “zombies,” NewsNation affiliate WPIX saw a sea of people with leg wounds, swollen hands and even missing limbs along notorious Kensington Avenue.

“Next thing you know, you wake up with these big-a** holes all over you,” said Jennette Freas, 48, who gets help with wound care at Prevention Point Philadelphia. “They just popped up anywhere. It’s not necessarily where you shoot up.”

Shawn Westfahl, coordinator for overdose prevention at the non-profit agency, said it’s believed the idea to mix xylazine — known as “tranq” — into the heroin and fentanyl supply started in Puerto Rico before the animal sedative turned up in Philadelphia.

Xylazine is now in 90% of Philadelphia’s drug supply, and a federal law enforcement source told WPIX it has also been detected in New York City drug stash houses.

“Adding a horse tranquilizer, something more sedating, makes it feel like it lasts longer,” Westfahl noted.

Art El Malik, who said he first tried fentanyl in Seattle before returning to his native Philadelphia, noticed several years ago that his drugs were turning a different shade of white or pink.

“We would wake up, and we would be completely sick,” El Malik told WPIX. “We’d see people walking around looking like animals, with their knuckles touching the ground.”

El Malik’s hands are swollen to about three times the normal size, and he said doctors have warned him about infection that could lead to amputation.

“Yeah, there is a possibility,” El Malik said. “A lot of my friends have lost their limbs already.”

WPIX saw one young man in a wheelchair who was missing his left foot.

Sean Anderson, 44, is originally from Delaware and said his shin recently had two holes in it before it healed.

“Delaware’s nothing like here,” Anderson said. “This is a whole other world.”

Anderson said he was turned onto pills and heroin by his mother when he was young. He came to Philadelphia after his mother died of the coronavirus. He said a local dealer gave him a free bag of dope.

“When I was leaving, some guy gave me samples and that’s what got me stuck,” Anderson said. “They had samples of free dope. I got one and I’ve been stuck ever since.”

Most of the people who live in tents, wheelchairs and among the garbage along Kensington Avenue are now hooked on two drugs: xylazine and fentanyl.

Remarkably, xylazine is not listed as a controlled substance by the Drug Enforcement Administration. The drug is monitored by the Food and Drug Administration, which issued a warning last November about the drug tainting the nation’s street drug supply.