Five men threatened a young Melbourne mother with a machete as they covered her mouth and warned her not to scream after ambushing her in the driveway of her home in the early hours of the morning.

It was the terrifying end to a Halloween-night crime spree that spanned six suburbs and began when three men were egged on the side of the road in South Yarra.

Chanelle Palmer, 29, pulled into her driveway after work about 3am on Thursday and was reaching for her work bag in the back seat, when the group of five thieves appeared beside her.

"[Five] young males came up behind me, covered my mouth, pushed me into the seat, pointed a 40cm machete at me and warned me not to scream and give up my keys," Ms Palmer wrote on Facebook.

"I did, 3 of them jumped in my car and drove off and the other 2 ran (possibly to another car) while I ran inside.

"My wallet, phone, everything was in my car. I'm okay, obviously I'm traumatised, exhausted and still in shock."

The thieves made off with Ms Plamer's grey Volkswagen, with the registration 1BR 4MW.

Residents in Melbourne's southern suburbs were assaulted, egged and threatened during the string of assaults on Halloween.

Police believe the same group of violent offenders may have been behind six separate attacks that took place between 5.30pm Wednesday and 3.30am Thursday.

Detective Senior Constable Lal Devinder Singh said police had identified nine victims so far with CCTV footage being analysed for clues.

"It was definitely planned. They have targeted vulnerable victims," he said.

"People who couldn’t defend themselves. You don’t expect someone to assault you while out for a walk or when driving home from work."

The first attack occurred on Coral Drive in Hampton Park, where a group of people in a white Volkswagen sedan threw eggs at three men walking along the street.

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They became involved in an argument and one of the men got out of the car and punched a pedestrian in the head. The offenders stole a phone and speaker from one of the victims and fled.

Just after midnight, about seven hours later, a group in a white sedan approached two men on Osborne Street in South Yarra and began talking to them.

They proceeded to punch and kick one of the men before stealing his phone, keys and wallet.

The victim, a 41-year-old Hawthorn man, was hospitalised with bruising and abrasions to his head.

At 12.50am on Thursday, a 24-year-old woman was approached by three men in a light coloured sedan on Carlisle Street in St Kilda. The men stole her phone before driving off.

Less than an hour later, about 1.30am, a 45-year-old man was at the intersection of Blessington and Carlisle streets in St Kilda when three men emerged from a Volkswagen sedan, tackled him to the ground and kicked and punched him.

They made off along Carlisle street with the victim's bag, which contained his phone. The victim suffered swelling and bruising to his head and torso.

Soon after 1.30am, a group arrived at a McDonalds restaurant on the corner of Jamieson Street and Nepean Highway in Cheltenham.

One man entered the restaurant wearing a mask and gloves. He demanded cash from staff, but the store managed used a broom to scare him off and he fled empty handed.

The last incident occurred about 3.25am at Ms Palmer's home in Patterson Lakes.

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Ms Palmer's mother Michelle Doran took to Facebook, saying she was grateful her daughter was not physically harmed.

"She was carjacked at knife point by five young men, four of African appearance and one Caucasian, she was assaulted and her car stolen," Ms Doran wrote.

"She is very traumatised.

"Please be careful if you drive a Golf," she wrote, "as the police believe they are targeting this model car."

Detectives believe the offenders used a white Volkswagen Jetta, registration 1FY 4HF, which was stolen from Murrayfield Street in Cranbourne East on Tuesday night.

A police spokesman said there was no initial indication the offenders were dressed up for Halloween.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.