A dramatic arrest in the main street of a Victorian town that left a man with such serious injuries he was placed in an induced coma is now the subject of an internal police investigation.

Key points: The man's friend, Damien Hall, has accused police of using unnecessary force during the arrest

The man's friend, Damien Hall, has accused police of using unnecessary force during the arrest He said there were six police officers involved, and at least four lay on top of his friend

He said there were six police officers involved, and at least four lay on top of his friend Victoria Police's Professional Standards Command will oversee the investigation into what happened, including the level of restraint used by police

The 33-year-old was flown to Melbourne's St Vincent's Hospital on Monday night.

A spokeswoman for Ambulance Victoria said he was suffering from critical head injuries after being arrested about 3.15pm on Monday.

WARNING: This story contains a graphic image some people may find distressing.

The man's friend, Damien Hall, has accused police of using unnecessary force during the arrest, which resulted in his head being split open.

Sorry, this video has expired Man arrested in Wonthaggi

But a witness said the man was throwing punches at police before the arrest.

Mr Hall said his friend was having an epileptic seizure and was swearing and frothing at the mouth in Graham Street in Wonthaggi, south-east of Melbourne, when police used capsicum spray to subdue him.

He said there were six police officers involved, and at least four lay on top of his friend until an ambulance arrived.

"I'm telling them I can calm him down when he's having a seizure, which I have done for ten years, but they were swearing at me and telling me to get away from them," Mr Hall said

"They put handcuffs on him, he's there frothing, he can't breathe, there's blood coming out of his mouth, blood pissing out of his head everywhere, the police sort of ganged him."

Victoria Police's Professional Standards Command would oversee the investigation into what happened, including the level of restraint used by police, a Victoria Police spokesman said.

The man was placed in an induced coma after the arrest. ( Supplied: Damien Hall )

Police confirmed the man was injured during the arrest. He was discharged from hospital on Tuesday.

Man was 'punching at car windows' after seizure: witness

Bass Coast Shire councillor and local real estate agent Brett Tessari works nearby and saw the man having the epileptic seizure.

"I went running up the street to see if I could help because, at first, I thought someone had been hit by a car," Cr Tessari said.

He then called an ambulance, he said.

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"His mother didn't want me to call the ambulance because she said her son has epileptic fits often and when he comes to he becomes aggressive, and that's exactly what happened," Cr Tessari said.

He said when the man eventually got to his feet, he started staggering up the street, punching at car windows and windscreens.

"He was quite distressed and disorientated," Cr Tessari said.

Police then arrived and detained the man, he said.

"But then all of a sudden he was up again, and really quite aggressive by now, and then I saw some big, wild haymakers [punches] being thrown, which missed the police.

"But once punches were thrown the police acted a lot differently, and grabbed him and detained him.

"Another police car pulled up and more police came running in and it all became quite a commotion after that.

"One of them grabbed him and threw him, wrestled him to the ground."

'There were kids everywhere'

Mr Hall alleged that, during the arrest, his friend was pushed against a metal bar, resulting in a split to his head.

Mr Hall said another police officer then grabbed the man's feet and dropped him to the ground, splitting his head open more.

The man was transported to the Wonthaggi Hospital and then placed in an induced coma for the flight to St Vincent's Hospital.

"Police have known him for his entire life, they know he has seizures. I don't believe he should have been manhandled this way at all," Mr Hall said.

"The excessive force used on him was outrageous."

Cr Tessari said the injured man already had blood on his hands when his seizure ended, but he did not have any blood on his face at that time.

"Once you start throwing punches at the police they've got to do what they can to protect themselves and it was end of school and there were kids everywhere and he was really aggressive," Cr Tessari said.

"I felt for him and I felt for his mother ... because I knew it wasn't going to end well.

"It was a really, really sad incident."