Officers were called to the wholesale store in Avonmouth just after 6.30pm after a teenage boy allegedly started to spray people with an unknown liquid.
Ten people, including the boy, complained of stinging or itchy eyes and skin, Avon and Somerset Police said.
The liquid is though to be a homemade chilli spray which contains no strong acid or alkaline ingredients.
Customers in a Costco in Somerset were rushed to hospital after being sprayed with a painful homemade chilli spray on Monday night.
A police spokesperson said: "People responded well to treatment and were discharged by the ambulance service at the scene.
