The search and rescue efforts following the deadly fire at Happy Cat Sanctuary on Long Island took a grim turn Monday. 

Rescuers with the Strong Island Animal Rescue League and Paws of War say another 54 cats were found dead on the property. That brings the total death toll to more than 160 animals. 

"Today has been a gruesome day as far as finding out how many more cats were actually in the house, once we got some access to the house," Frankie Floridia, with Strong Island Animal Rescue League, said in a social media video Monday. 

"When we set out this morning, the goal was always to see if there were any injured cats post-fire that went back into the rubble," added Robert Misseri of Paws of War. "Thank God there were no living cats that were injured, but 54 deceased additional cats, over the 100, have been removed. Very difficult for our team here today."  

Misseri said three of the deceased cats belonged to homeowner Chris Arsenault, who was also killed in last week's fire.

Vets, volunteers treating surviving cats

More than 160 surviving cats are currently being treated at a warehouse off-site, and approximately 60 more will be headed there shortly. 

"We vetted, vaccinated, snap tested, microchipped... cut nails, cleaned up, gave shots of antibiotics to cats that needed it," said Happy Cat Sanctuary volunteer Lisa Jaeger, adding, "There isn't going to be enough hours in the day for me to thank the Long Island people who have stepped up to provide food, prayers."

The rescuers say they will continue to search the neighborhood for any remaining cats, and then adoptions will eventually be handled by Happy Cat Sanctuary at the warehouse. 

The fire is not considered suspicious, and investigators say it may have been caused by a propane space heater.