A 44-year-old man has been charged following a stand-off with police in a major operation in the Blue Mountains.

Around 10am, police blocked off a street in Katoomba amid reports of a siege, with an armed man barricaded inside a block of units.

Police say emergency services had responded to reports of concern for the welfare of a woman, who had been threatened by a man known to her.

She fled the home at the corner of Lurline Street and Leichhardt Street, and was treated by paramedics before being transferred to Katoomba Hospital with minor injuries.

A man inside the property was arrested following three-and-a-half hours of negotiations.

Vision just in from the scene. The Police operation is ongoing. #9News pic.twitter.com/YC5MPbEAxC

— 9News Sydney (@9NewsSyd) January 19, 2021

Seven News crime reporter Evan Batten told Jim Wilson some police remain at the scene, at the basement unit of the hostel.

“He [was] armed with a small axe, or a hatchet of sorts.”

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Earlier, local resident Tom told Deborah Knight he was evacuated from his home by police, but said officers have been “tight-lipped” about the details of the operation.

He heard police earlier calling up to the person in the building, before breaking through a window.

“Obviously there is some kind of a threat, otherwise they would’ve gone straight into the building.

“I feel a little bit weird … I’m literally standing here on the street in my pyjamas.”

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Image: Nine News