Man arrested after Melbourne shooting

An 18-year-old man has been arrested by police investigating the shooting of another teenager at point-blank range in a Melbourne shopping centre car park.

An 18-year-old from Cheltenham remains in a critical condition after he was shot in the chest on Wednesday night.

It's believed he was hit during an altercation between up to 10 people at Vermont South Shopping Centre.

The Warrandyte man was arrested on Thursday evening, but was released after being questioned by officers.

A vehicle has been seized, but police say the gun has not yet been found.

Detective Senior Sergeant Ian Shepherd said it was worrying that the shooter was still at large.

"Quite clearly the community should be concerned," he told reporters on Thursday.

So far police have been unable to speak with the victim, and his brother has been reluctant to assist police.

The man's brother hasn't been ruled out as the shooter.