A teenager has been arrested for allegedly taking part in the armed robbery of a petrol station.

Hawke's Bay Detective Sergeant Darren Pritchard said at 6am yesterday morning three armed robbers entered the Z Petrol station on Kennedy Rd, Napier and demanded goods from the attendant.

The trio then took off with a small amount of property.

The attendant was left shaken but was not injured. Victim Support had been working with the attendant.

A 17-year-old Napier resident has been charged with aggravated robbery and will appear in Hastings District Court next week.

Pritchard said it was "pleasing" to have found one of those allegedly responsible for the robbery but said help was still needed from the public.

A black Nike sports bag containing items of interest was believed to have been dumped somewhere between the Petrol station and the suburb of Marewa, he said.

"If you have found the bag or have any information about the robbery call police on (06) 873 0500 or anonymously phone Crimestoppers on 0800 555 111."