SAN ANTONIO -- A female Realtor was raped by a man posing as a homebuyer, Bexar County sheriff's officials said.

The woman told investigators that a man in his mid-40s visited with her in a portable office building located in a Northwest Side subdivision for about an hour late Wednesday afternoon when he pulled out a knife, said Bexar County Sheriff's Office Lt. Dale Bennett.

The man then forced the woman into a rear office and sexually assaulted her, Bennett said.

"She was locked up and bound and gagged for about six hours before a security guard found her," Bennett said.

The woman was able to provide a "pretty good" description of her attacker, Bennett said.

The woman is expected to view a photo lineup on Friday that will hopefully produce a suspect, Bennett said.