A schoolgirl from Todmorden was left shaking and crying after she was followed by a man holding a knife on her way home from school.
The 14-year-old said she felt she was being followed by the man, who did not speak to her, shortly after 3pm on Friday.
He had a bandanna covering his face and was carrying what the girl described as a 'big carving knife'.
A similar incident was reported a few months ago.
The girl's father, who did not wish to be named, said: "She was very upset by it, obviously.
"She ran home and was crying and panicking. She's alright now, she's resilient, but it was a huge initial shock.
"We don't know anything about this man or what sort of issues he might have - we don't want some sort of witch-hunt.
"But it makes me sick to my stomach what sort of damage could have been caused if something had have happened."
Shortly after the incident, the man is believed to have made his way up Victoria Road, opposite Todmorden Cricket Club.
A West Yorkshire Police spokesperson said: "Police received a report that a member of the public had seen a man in possession of a knife while walking on Harley Street, Todmorden on Friday (18/01).
"The incident is believed to have happened at around 3.15pm. Enquiries remain ongoing.
"Anyone with information is asked to contact police on 101, quoting crime reference 1319035552."