A man is accused of going into a woman's apartment and trying to sexually assault her when she came back from walking her dog late Sunday night.

It happened around 11:45 p.m. The woman said she left her door unlocked when she walked her dog at her apartment complex in the 7900 block of Westheimer.

When she came back, she told police that she noticed a light was on in her guest bedroom.  She said the door was open and she said a stranger was inside her home. 

She ran and told her neighbors. The neighbors said they all went back to her apartment, and that's when they said the victim, a woman in her 30s, was attacked. She said the victim told them to run and call for help.

"She said, 'No, no, call the cops. Go and try and get my phone. It was in my bedroom,'" said neighbor Zafar Ali. "So we call the cops."

Police said when they arrived, they found Luis Sierra, 29, trying to sexually assault the woman. He was arrested and charged with attempted sexual assault.  

Police are waiting for hospital tests to come back.