Surveillance video shows 21-year-old Eduardo Gonzalez approaching a woman as she cleaned the facility early Wednesday morning.
Gonzalez asked if she was the only one there, and when she replied yes, he ordered her to have sex with him.
When she refused, he pulled out a handgun, pointing it at her.
Officials say he pushed the woman into another room and forcefully tried to undress her.
She fought him off, eventually overpowering him and then ran for help.
On Thursday night, the 21-year-old is in custody for the assault.
Authorities later found the gun he used and determined it was fake.