Wildfires that have ripped through a rural area east of Austin have not only destroyed hundreds of homes, but caused major damage to a historic state park, along with an endangered species of toad there, wildlife officials said on Wednesday.

Among the casualties are two Depression-era scenic overlook structures and a 1930s rain shelter that were largely irreplaceable.

In addition, the park was the "final stronghold" of the endangered Houston Toad -- the first amphibian to be granted protection under the 1973 Endangered Species Act, said Mike Cox of the Texas Parks and Wildlife Department.

"We have great concern about it," Cox said. "It will be a while before our biologists can actually get in there and do an assessment to see if our worst fears were realized."

The 5,900 acre park is located in the middle of 34,000-acre fire zone and was over 90 percent damaged, Cox said.

The Bastrop County Complex fire has burned since Sunday, destroyed 785 homes and caused the evacuations of some 5,000 people.

The 14 historic Civilian Conservation Corps structures on the park grounds, including campground buildings and a historic sawmill, were saved by what Cox called a "heroic" effort by firefighters who bombarded the buildings with water and fire retardant from the air late Tuesday night.

Cox said it's unclear how severe the damage will be to the park and when it will reopen.

"This Great Depression era architecture is irreplaceable," Cox said. "The original architecture, built with the pine that was sawed right here on the park, is truly a part of American folklore."