Two people were taken to hospital after a woman approached them with a bag, causing them to feel unwell.
Avon and Somerset Police said they were called to reports of a woman approaching people in Stall Street in Bath at around 2.30pm BST.
Two people experienced difficulty breathing and itchy eyes.
A police spokesman said officers were working with paramedics and firefighters and had “well-rehearsed plans to respond to such incidents”.
