A large explosion near a Greymouth roundabout early yesterday morning was caused by a device made from fireworks.
It was just one of a number of incidents Greymouth police were called to over the weekend involving the misuse of fireworks.
Fireworks went on sale on Saturday and by 5pm aletterbox in Elizabeth Street was damaged when crackers were let off inside it.
Three hours later, fireworks were fired at a house in Dowling Road, Paroa, from a party at a neighbouring house. Police were called but all those interviewed, aged in their late teens to early 20s, denied aiming the fireworks at their neighbour.
About 1am yesterday, night staff at the Z Energy service station in Whall Street reported hearing a large explosion, followed by smoke billowing up in the Tainui Street area.
West Coast police intelligence supervisor Rodney Beckett said they now believed the explosion was caused by a device constructed from fireworks, and had been let off by a large group of people, who quickly left the scene when they realised police were watching them.
Police did not catch anyone involved, but did find the remnants of fireworks at the scene.
Westport police also investigated a number of reports of fireworks being shot out of moving cars.
Mr Beckett said police were not opposed to people having fun and using fireworks responsibly, "but will take a stance if fireworks are used irresponsibly and charges are a possibility".
"One big no, no is mixing fireworks with alcohol consumption - this combination can be very lethal."
Fireworks will be on sale until tomorrow, Guy Fawkes night.