A truck laden with chemicals burst into flames in Hamilton last night, causing a series of explosions that shook houses several kilometres away.
Thick clouds of potentially toxic smoke spilled over parts of the city as firefighters were forced to retreat from the blaze.
Emergency servicesset up barriers around the accident area, and environmental and health protection officers were called in to identify the chemical risks amid fears of a spill into the Waikato River.
Hamilton's deputy fire chief, Martin Berryman, said there was a possibility that some chemicals flowed into the river.
Eight fire engines from the Waikato area went to the accident, at the intersection of Cobham Dr and Normandy Ave, just before 8pm.
Firefighters wearing breathing apparatus and protective suits were forced to pull back from the truck as its cargo began exploding, and had to let the fire burn until the toxicity of the chemicals was known.
It is believed the truck and trailer unit was carrying pharmaceuticals, paint and animal remedies.
Hamilton resident David Cooke, who lives about 2km from the fire, was dozing in front of the television when he was woken by the first huge explosion.
"It really shook our house," he said.
"You could feel the percussion in your chest."
The explosion happened near a park by the Waikato River.
The accident was close to Waikato Hospital, but the hospital was not threatened.
No houses had to be evacuated.
It was not known what caused the fire, in which the trailer was detached from the truck, but it is believed no other vehicles were involved.
Late last night the fire was out and a vehicle with a suction device was called in collect spilled liquids.
The material was removed for analysis.
Firefighters at the scene went through a decontamination shower after controlling the fire.
