A fire swept through the Humane Society of Durham Region shelter early Wednesday, leaving about 180 animals dead, police said.

In its wake, those who cared for and loved the animals inside were heartbroken. Teen volunteers could only hug each other, sob and place flowers outside the charred, boarded-up building on Wednesday afternoon.

"I was the investigator. I brought in the animals that were abused," said Debby Houghton.

"A lot of these animals were abused in Durham region. They were starving or neglected and came here to be safe," she said, her voice cracking with emotion.

Another woman noted that many of the animals had to fight to stay alive, only to die from the heat, smoke and flames.

Fire had engulfed the building when firefighters arrived about 2:30 a.m.

Emergency crews managed to save nine dogs, a rat and two cats from the building, located on Waterloo Street in Oshawa. About 140 cats died from smoke inhalation, as did three dogs and about 40 small animals including some rabbits and a guinea pig.

The damage to the building is extensive, police said in a news release.

"The building suffered extensive fire and smoke damage estimated at approximately $250,000," it said. "The cause of the fire has not been determined and remains under investigation."

The animals that were saved were sheltered in police vehicles until officers with Oshawa Animal Services arrived to rescue them.

The pets are now at a 24-hour animal hospital in Whitby where they are being examined.

"This is a horrific event and our hearts go out to the Humane Society of Durham Region," says Kate MacDonald, CEO of the Ontario Society for the Prevention of Cruelty to Animals.

"The SPCA will be assisting the Humane Society in any way we can during this emotional time."

With a report from CTV Toronto's Tom Hayes