Philadelphia (CNN) Hazel Donnelly was taking her husband to the doctor when they got a call that their apartment building was on fire.

Her first thought was about her 17-year-old cat, Kramer.

"I don't have children on my own, so my cat is like my child. I became hysterical," said Donnelly, 50. "What if (he) didn't make it?"

Once she arrived home, Donnelly implored firefighters to get her cat, but they were busy trying to control the blaze.

Then Red Paw Emergency Relief arrived. The nonprofit assists pets and their owners when disaster strikes. Jen Leary, a former firefighter who founded the group, met with building residents and, once the fire was out, retrieved the animals.

Jen Leary's nonprofit responds to residential disasters such as fires, gas leaks and building collapses.

"Everyone who received their pets started to cry," said Donnelly.

No one was hurt, but the Donnelly's apartment had severe damage, and they weren't sure where they were going to stay. Donnelly was thrilled to learn that Red Paw could provide free short-term care for Kramer.

"When (someone) loses everything in a fire, they shouldn't then be forced to lose their pets -- their family members -- as well," Leary said. "Letting them know, 'We'll take care of your animal like it is our own,' it means the world to people."

Since 2011, Leary and her group have provided emergency assistance to nearly 1,000 animals and their families throughout southeastern Pennsylvania.

Like the Red Cross, but for animals

Several years ago, Leary began working as a firefighter and American Red Cross volunteer. She would often arrive at a disaster scene and see traumatized survivors struggling to care for their pets.

"They'd ask, 'What am I supposed to do with my dog? Who is going to help find my missing cat? How is my pet going to get medical care?" said Leary, 36. "There just wasn't anyone there to help the other part of the family."

Pets were sometimes taken to shelters or abandoned. The situation broke Leary's heart.

When (someone) loses everything in a fire, they shouldn't then be forced to lose their pets -- their family members -- as well. Jennifer Leary

After a devastating fire in 2011, Leary formed her organization and teamed up with the local chapter of the American Red Cross. Now, whenever the Red Cross responds to a disaster and discovers that an animal is involved, they call Leary. She believes it's the only partnership of its kind in the United States -- one she hopes to replicate in other cities.

Always on call

Leary's group responds 24 hours a day, seven days a week to residential disasters such as fires, gas leaks and building collapses. Leary answers nearly all the calls herself. Her firefighter background gives her unique privileges.

"I'm allowed into situations that other people might not be," Leary said. "Once the fire is out and they're just hitting hot spots, I'll talk to the chief, and if they say it's OK, I'll go in."

Rescuing animals is only part of what Red Paw does. Through a network of 400 volunteers, boarding facilities and veterinarians, the group provides emergency transportation, shelter, pet supplies and medical care to any pet involved in a disaster -- all for free.

Leary's home is the first stop for most animals that don't need immediate medical care. They usually stay with Leary for a few days while they get vaccinated, spayed and neutered, if necessary. Then they are moved to foster homes until their families are ready to take them back.

The group's roster of animals has also included rabbits, ferrets, fish, birds, turtles and other reptiles.

Reuniting families

Red Paw, which runs on donations, provides care for most animals for around 60 days. The group's caseworkers check in with the owners weekly. When families are reunited with their pets, they receive a kit of supplies.

"Food, cat litter, bowls, medicine, whatever they need," said Leary. "We want to make sure that they're starting off the right way."

If a family can't take their pet back, the group will find the animal an adoptive home.

Red Paw cared for the Donnelly's cat for more than three weeks.

"I cried when we were reunited," said Donnelly. "They went above and beyond. I am so grateful."

For Leary, helping families and their pets is what her work is all about.

"My hope is that it's a fresh start, and they can move forward together," she said. "After going through such a sad thing, it's so good to have a happy ending."