The man said he saw lots of broken glass, shoes, clothing and car parts spread across the ground. Police were speaking to people in the area and a nearby petrol station was full of cars and people.
A woman at the supermarket said she was packing her car when she heard a "loud bang" - followed by another - about 9.15pm.
She thought thought it was fireworks until she saw people running.
"I quickly jumped in my car and another a few shots happened again," she said.
Scared to go anywhere, the woman said she hid in her car.
"I just heard people screaming and cars zooming off."