Police are continuing to search for a person of interest in relation to a series of incidents in the north-west this morning.

Police were notified by several members of the public of a man acting erratically in Macfie St Devonport about 9.15am, knocking on doors and demanding keys to their vehicles.

He then left in a white Toyota Fortuner, registration L29QT.

Police were then notified of a robbery at a Railton service station about 9.50am, where a quantity of cash was taken.

A short time after that, police were notified of a stolen motor vehicle in Kimberley, which police now believe he is driving- a silver Alfa Romeo, registration C86EE.

No members of the public were physically injured in either incident, however police urge members of the public not to approach the man but to contact police on 131444.

Police including helicopter resources are currently in the area searching for the vehicle.

The man is described as 5ft 8, with short hair, olive complexion and facial tattoos.

Anyone with information should contact Devonport Police on 131444 or report to Crime Stoppers on 1800333000 or crimestopperstas.com.au