By Molly Daly

PHILADELPHIA (CBS) — Philadelphia police are asking for the public’s help in identifying the man they say sexually assaulted a young woman inside her home in the city’s Frankford section.

It happened just before noon Monday in the 4900 block of Mulberry Street.

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Police say the 18-year-old woman was alone in the home when a man claiming to be a Verizon worker knocked on the door. She told him to come back later. Not long after that, an alarm sounded and he was inside the house.

“She told the male he had to leave. He came upstairs, where he sexually assaulted her,” said Special Victims Unit Captain Mark Burgmann. “She was able to grab a sword that she had inside the house, told the male he had to leave, that her mother was coming home. The male then fled.”

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Investigators are hoping someone recognizes the suspect from video on the Philadelphia Police Department’s YouTube channel.

“We’re just asking them to give us a call before he hurts somebody any worse than he already has,” Burgmann said.

He also has some advice.

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“Make sure you keep your doors locked at all times,” Burgmann said, “and be very careful with whoever comes to your door.”