A man in a hoodie was also seen running down the street, she said.
Police who attended the incident told her the window had probably been smashed by people riding in a supermarket trolley.
An extremely intoxicated man who returned to the scene told police his friend had smashed the window, the passerby said.
The owner of the shop, who wished to be known as Mike, said he arrived at about 9.40pm to clean up the mess.
He was unsure if the damage would be covered by insurance.
"I'm always pissed off if it's going to cost me money."
"It's more the inconvenience of it really ... what can you do? It's just going to cost -- that's the end of it."
The last time the window had been smashed was about 12 years ago, when a man tried to break in to steal a bike, he said.
Senior Sergeant Gordon Crawley said police were seeking someone in relation to the smashing of windows at Percy's Mart and the Salvation Army store, which also had its window broken on Tuesday.