Officers from Ringwood crime investigation unit attended Smart Way Mobile Accessories on Mt Dandenong Road at about 11.30am after a man aged in his 30s entered the store armed with a knife and stole a small amount of cash and a mobile phone.

He is described as six-foot tall and was scene wearing blue jeans and a dark coloured jumper.

However, while police attended the store, the occupier was caught operating an illegal DVD business.

Detective Leading Constable Damien Morris said police seized thousands of burnt DVDs. He said the woman, aged in her 40s, would be interviewed and was expected to be charged.

Information to Detective Leading Constable Morris at Ringwood CIU, 9871 3057 or Crime Stoppers, 1800 333 000.