REGIONAL Investigations Unit Detectives are searching for a man linked to an armed robbery that happened in Ballajura last night.
About 10.30pm, the man entered a petrol station on Illawarra Crescent.
He threatened a staff member before going behind the counter while holding a crowbar.
He assaulted the staff member before forcing the till open, taking some cash and leaving the scene.
The man is described as fair-skinned, between 30 to 40 years of age, 180cm tall with black-grey hair.
He was wearing a dark, hooded jumper and blue jeans.
Police urged anyone with information to call Crime Stoppers on 1800 333 000 or to make a report online at crimestopperswa.com.au.