A third teenager has been arrested over a violent carjacking in East Malvern, in which a Mercedes driver was allegedly attacked with a hammer. An 18-year-old man from Hampton Park was arrested last week over the carjacking on Waverley Road in Malvern East about 3.30am on June 21.

He faced Melbourne Magistrates Court on June 30, charged with armed robbery, intentionally and recklessly causing injury and theft of a motor car, as well as other assault related offences.

His case was adjourned, with his bail application to be heard at a later date.

Two other teenagers have been arrested over the incident, one of whom has faced the children’s court.

Police have been told the 40-year-old victim was slowing for the lights at the intersection of Belgrave Road when another car nudged the back of his Mercedes.

The car behind allegedly hit his vehicle twice more, before the Mercedes driver got out to see what was going on.

The victim was allegedly grabbed by three men, who jumped out of a Kia, before pinning him to the ground and rifling through his pocket for keys. It is believed the victim was also attacked from behind with a hammer.

Detectives are still investigating whether other people may have been involved.

Another car, a white BMW, was in the vicinity at the time and may have been involved as back-up. Police also received information about the three cars travelling in a convoy in Footscray about an hour later.

The arrests come in the wake of a series of violent carjackings across Melbourne, which prompted Victoria Police to set up Operation Cosmas.

“At the start of May we rolled out Operation Cosmas, drawing together investigators under the umbrella of Crime Command,” Senior Constable Julie-Anne Newman said.

“Day and night patrols are being conducted at high risk locations to prevent offences taking place.”

Officers with Operation Cosmas have so far made 60 arrests.