Daniel Tuski Bertrand, pictured, 25, was arrested and charged with 4th-degree assault, a misdemeanor offence

Shocking security camera footage shows a man pacing back and forth swinging his arms before hitting the woman twice while her back was turned.

The unnamed 44-year-old woman reportedly suffered a broken eye socket in the attack at around 1am on Monday in the downtown area in Portland, Oregon.

Daniel Tuski Bertrand, 25, was arrested and charged with 4th-degree misdemeanor assault, according to KOIN 6 News.

The footage, shows the woman walking towards the walkway and reaching over to a nearby bouncer shortly before the apparent attack.

The man, allegedly Bertrand, continuously crosses his arms in front of his body and appears to wait until the woman looked away before striking her in the back of her head.

A second hit to her face causes her to fall into the arms of a man nearby.

As men nearby surround the woman, the attacker jumps around on the ground before walking away.

'I’m just happy to be alive and to have my eyesight,' the victim told KOIN 6 News.

The man (left) can be seen swinging his arms in front of his body before he strikes the woman (center) once from behind to the back of the head and an additional hit to the face

The moment the man (center) strikes the woman while her back is turned, in shocking security camera footage captured in Portland, Oregon

Bouncers from the street, where the alleged assault happened on Southwest 2nd avenue and Ankeny Street, shared the footage.

One of them, Jeremy, spoke to KGW8, explaining that the man was dancing to loud music prior to the incident and 'just came out of nowhere and socked her.'

'She didn't do anything to him, say anything to him, just looked into his direction and then started talking to the bouncer.'

Jeremy told the site that he used pepper spray on the attacker after he became physical, but it didn't work.

But instead of pursuing the attacker he decided to help the victim until paramedics arrived.

Jeremy told the site: 'She would come back into consciousness, she was unaware of what was going on.

'All she knew was that she was in a severe amount of pain and couldn't see because of the bandages."

He claims to have shared the footage to raise awareness of a spike in violence in the area.

Since being uploaded on Thursday the clip has been seen more than 40,000 times.

Bertrand was charged, and has since been released. Multnomah County District Attorney’s Office told KOIN 6 that he is homeless.

DailyMail.com have reached out to Portland Police Bureau for comment.

The woman falls into a man nearby, as the attacker (front center) walks away, initially pursued by a group of men