WATCH: Drone flies over Pet Alliance of Greater Orlando after fire

Officials say more than 20 cats are dead after a massive fire broke out at the Pet Alliance of Greater Orlando facility off of Conroy Road on Wednesday evening.

The fire is believed to have started around 10:30 p.m. near the cat room. 

Firefighters said the blaze had consumed 50 percent of the property at 2727 Conroy Road, and flames "were through the roof." A partial roof collapse occurred.

RELATED: Over 20 cats killed in fire at Pet Alliance of Greater Orlando

In an update on Thursday morning, an Orange County Fire Rescue official said that the layout of the building provided some obstacles for firefighters, describing it as "kind of like a maze in there." He also said at some point, the fire got so overwhelming that crews had to be pulled out.

There is extensive damage to the building but no firefighters or deputies were injured though, he added.

In a Facebook post from the shelter on Thursday, they confirmed that 23 cats were lost to the fire. 

It is still not known how the fire started but the state is investigating. Officials do know that the fire started in the front of the clinic though.

RELATED: Bodycam: Deputy rescue dogs from Pet Alliance of Greater Orlando

The shelter is in need of donations for the animals including wet cat food and blankets. You can drop them off at the Sanford location at 2800 County Home Road.

Watch FOX 35 Orlando for the latest Central Florida news.