Two women have thwarted an armed bandit who tried to steal their handbags in separate incidents.
Police say the first offence happened about 11.30am on Monday outside South Lake Shopping Centre, when the man pulled a knife on a 77-year-old woman.
"A 77-year-old woman was walking at the rear of the South Lake Shopping Centre, when she was approached by a man in his vehicle," she said.
"The man brandishing a knife and threatened to stab her if she didn't hand over her hand bag."
The woman refused to hand over her property and the man fled.
About an hour later, the man allegedly tried to mug a 79-year-old woman in the car park of Spearwood Shopping Centre.
"A man drove his vehicle towards the woman, reaching out of his car and grabbing her hand bag," the police spokeswoman said.
"The woman wouldn't let go of her bag and a struggle developed, resulting in her falling to the ground still holding her bag.
"She suffered minor bruising and lacerations to her body. The man fled the scene in his car."
About 10.45am on Wednesday, he allegedly stole a 57-year-old woman's handbag from her shopping trolley outside Kwinana Hub shopping centre.
Police say he stole eight packages from an unlocked Australia Post van, as well as the driver's valuables.
A 20-year-old Parmelia man has been charged with attempted aggravated armed robbery, attempted aggravated robbery, theft of mail articles and stealing.
He is due to appear in Fremantle Magistrates Court next Friday.