A hunt has been launched for a man who chased a woman while wearing a "Chucky-style Halloween mask" in Philadelphia.

The incident took place at around 5.30am (10.30am in the UK) on 12 August, according to the Philadelphia Police Department, with the victim - a 40-year-old woman - suffering an injury while being chased.

Officers have named the suspect as 22-year-old Zymire Hughes, and said he may have fled Pennsylvania for California and Nevada.

"There is nobody in the world who should be trying to imitate what this scared man, who's running, is doing now," Philadelphia District Attorney Larry Krasner told reporters at a conference.

"He's a punk. I mean, that's the bottom line. He's a punk who scared a lot of people for no good reason, and we're not going to tolerate it."

Philadelphia police Captain Jason Smith added on Thursday that Hughes is alleged to have held up a phone and repeatedly asked the fleeing jogger, "Are you ready to die?"

He then said: "She's startled. He repeats that phrase. She turns around, runs away from him, and in the process she severely injures one of her legs.

"And it's going to require extensive medical treatment, from what I understand, in order to treat the injuries that she has sustained."

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After the chase, Hughes allegedly went into a metro station, where he was asked to remove the mask by police.

"Underneath that Chucky-style Halloween mask, he's got a black COVID-style mask underneath of that, which he never removes," Mr Smith said, referring to the killer doll from the Child's Play horror franchise.

The captain also said it's clear that Hughes is "attempting to the best of his ability to conceal his identity".

Authorities in Philadelphia said they believe Hughes has pulled this stunt previously and are asking other potential victims to come forward.