JACKSONVILLE, Fla. -- The Jacksonville Humane Society has begun to work toward rebuilding after a fire gutted its Southside headquarters, killing nearly 100 animals.

According to the Jacksonville Fire-Rescue Department, the fire broke out at about 2 a.m. Saturday and nearly 70 firefighters responded to the blaze.

The roof of one of the buildings collapsed in flames as the fire destroyed the building on Beach Boulevard.

Humane Society Executive Director Leona Sheddan estimated 173, mostly dogs and cats, were in the facility, and said 71 cats and 24 dogs and puppies were killed in the fire.

"Knowing that animals that were here in our care died in our care in a no-kill shelter breaks our hearts," Sheddan said.

Firefighters rescued as many animals as possible before fire drove them back, Jacksonville Fire and Rescue spokesman Tom Francis said.

"Our protection of life policy extends to all living creatures," Francis said. "It's an emotional scene. When you have defenseless animals in danger, you see even the most seasoned veteran firefighter feel some melancholy."

Four firefighters were hospitalized with minor injuries. The most seriously injured was in the building when the roof collapses. He was transferred to the Shands-Gainesville burn unit.

Sunday afternoon, the focus shifted from Saturday's tragic fire to the future as dozens of people stopped by the Humane Society to offer their support through donations.

The fire touched the hearts of many people in Jacksonville who told Channel 4 that they still couldn't believe that cats and puppies were killed, and that other dogs were set free as the flames roared above them.

"My brother-in-law and sister told me about it at lunch and I could not eat," Sue Dwelle said through tears. "I just felt so bad for them. I know it was scary. I heard my brother-in-law say the dogs were all running around here, but they hopefully retrieved them all."

"Well, I got a little dog from here 12 years ago and I had to have her put down in February. It just breaks my hearts for the dogs and cats, so I am doing what I can," said Pat McAdams.

In addition to losing animals and kennel facilities, Sheddan said the Humane Society lost medical equipment and its supply of medications.

The blaze destroyed the main building, valued at about $1 million. Other buildings on the 10-acre property, including the dog kennels, are still operational, Sheddan said.

Determining the cause of the blaze will be difficult because of extensive damage to the building, said Francis. The blaze did not appear to be suspicious, he said.

Humane Society officials said they have plenty of food and dog beds but they're asking for cash for medical equipment and medications. People can donate at the Humane Society Thrift Store on the corner of Beach Boulevard and Foster Drive or go to any Wachovia bank and donate to the Humane Society Fire Fund.

The surviving animals are being held at the Humane Society's clinic and some will be in foster care. They hope to be able to get dogs back in to kennels that weren't destroyed and reopen for adoptions on Tuesday.