One person is assisting police with their enquiry.
The entire service station was alight within minutes.
Police would like to hear from anyone who saw suspicious activity.
They were injured on Saturday.
The gun was reportedly presented, but not fired.
More than 100 homes have been deemed uninhabitable due to flooding.
"When I handed the [food parcel] to her, she burst into tears. She was so moved."
The city was badly flooded earlier in the week.
Almost 70 homes have been deemed uninhabitable.