Police have charged three youths (aged 15, 16 and 16) and two adults (both aged 18) over an attempted armed robbery and an aggravated robbery in Hobart overnight.

Police will allege the group entered the 24-hour convenience store shortly before midnight, and demanded cigarettes and cash before leaving empty handed.

The group reportedly returned a short time later armed with a knife and a baton, and left the scene with a significant amount of cash and cigarettes.

Police apprehended the group early this morning.

They have all been charged and the youths and one adult will appear in after hours court tonight, with the second adult due to appear on 20 December.

Detectives from Hobart CIB are investigating the matter, and particularly want to speak to a witness who reportedly saw the group leave the scene in a grey Holden Cruz.

Anyone with information about the incidents, or who saw a grey Holden Cruz in the greater Hobart area around midnight is urged to contact Hobart CIB on 131 444.

Information can also be provided to Crime Stoppers at crimestopperstas.com.au. You can stay anonymous.