WARNING: The following video includes disturbing content

A farm in Pennsylvania that supplies animals to PetSmart and Petco has been slaughtering animals by the hundreds — cruelly gassing them with carbon dioxide or leaving them in freezers to die slowly, a report says.

“Their screams could be heard across the room,” a report by People for the Ethical Treatment of Animals claims.

Disturbing video posted by the animal advocacy group shows the alleged atrocities unfolding at Holmes Farm, a massive supply mill in Barto that provides thousands of hamsters, rabbits, gerbils, chinchillas, ferrets and other furry creatures to countless pet stores across the eastern US, including PetSmart, Petco and Pet Supplies Plus.

“The animals — thousands of whom had already been subjected to a grueling overseas trip in shipping crates — were confined to crowded bins or cages in Holmes Farm’s filthy, windowless warehouses,” PETA says. “The buildings reeked of urine and feces, and one building’s floor was spattered with blood … PETA’s observer never saw any animals receive veterinary care at the facility, despite repeatedly alerting the manager to obviously sick and injured individuals. Instead, workers piled dozens of animals — ranging from rats and gerbils to guinea pigs and even a rabbit — at a time into a feces-smeared cooler and crudely gassed them with carbon dioxide.”

PETA also claims that workers at the farm refused to check the animals for signs of life before dumping their bodies in the trash or wrapping them in plastic bags to sell as “feeders.”

“Some sick or emaciated animals languished for days without care, including rabbits who eventually died in cages,” says PETA. “Some rats evidently carried rat-bite fever — a disease that is potentially fatal, is transmissible to humans, and has already led to two lawsuits against Petco.

“Live rats were stuffed into plastic zipper bags or tossed onto plastic lids and put in a freezer, slowly freezing to death even as some frantically tried to claw their way out,” the group added. “Many of these animals were later sold as food for snakes and other carnivorous reptiles. Even after PETA notified Petco that a notice to its suppliers was in order to ensure that American Veterinary Medical Association (AVMA) guidelines were followed, the cruel killings continued.”

Petco claims to have severed all ties with Holmes Farm, which is currently under investigation by the US Department of Agriculture.

Despite this, PETA’s eyewitness investigator documented that hundreds of animals were packed up for company stores as recently as January 5 — more than a month after Petco representatives were last seen at the facility.

“Petco stores were ordering and receiving animals by the hundreds from Holmes Farm, even as the USDA began its inspection,” the group claims.

Since the scathing report was posted, Petco has tried to explain itself on Facebook.

“Holmes is no longer a supplier to Petco stores,” the company said in response to a user’s comment. “We take animal care very seriously and we expect the same of our suppliers. In short, we hope you’re happy to learn that we have ended our relationship with Holmes Chinchilla Ranch.”