The man behind a shocking racist rant in a Centrelink office in Adelaide’s north has recorded a public apology for his actions.

He claims his rant came from his struggle with mental illness.

A friend told 9NEWS he is distraught and has never behaved that way before.

The rant shocked those there on the day including young children and the hundreds of thousands of people who have since viewed it online.

“Quick, run away over there people because a racist person is freaking out,” he was captured saying on video.

“I didn't vote for multiculturalism ... did I?”

Police were alerted after a staff member pressed a duress button. (Facebook) (9news)

Troy issued the apology after witnessing his rant on video. (9NEWS) (9news)

Among those who viewed the video was the man himself.

“I'm apologising for what happened on Monday. I've only just seen the footage of what happened on Monday,” he said.

What happened was a vile and threatening outburst, directed at staff at the Salisbury Centrelink office and clients who had been there at the time.

“I'm going to smash all of you,” he said.

The video statement was sent to 9NEWS by a friend.

In it, the man named Troy explains he suffers from depression and anxiety - and had gone to the Centrelink office for help.

“I didn't have my medication and that's why I went into Centrelink to sort it out,” he said.

“So if I offended anyone or upset anyone, I am truly sorry.”

Friend Chantelle Berlemon says the apology is a genuine one.

“I have never heard anything like that come out of his mouth,” she said.

Troy has told Ms Berlemon he has absolutely no recollection of the incident, and was in tears after he watched the video.