A chemical spill from a container at Napier Port halted terminal operations this morning.
Seven fire engines were called shortly before 10am and crews focused on containing the chemical to stop it getting into the waterways.
A Fire and Emergency New Zealand spokesperson said the spill was believed to be a type of polyline chemical used to make polystyrene.
"I understand a blistered container within a larger shipping container has split and caused the spill."
He said no evacuations were required.
A spokesperson for Napier Port said the area was cleared of workers and container terminal operations were suspended for much of the afternoon while FENZ managed the clean-up.
"Limited operations resumed at our container terminal this afternoon.
"We have also extended our gate hours for late receivals this evening to assist customers."
Full port operations were expected to resume tomorrow provided Fenz gave the "all-clear".
He said the substance had leaked from a container that was unloaded from a vessel this morning. The cause of the spill is still being investigated.
The substance was used in the production of asphalt and has a flammability risk, but did not pose any immediate health risks, he said.
Hawke's Bay Regional Council's pollution response team was also called to the spill, HBRC general manager policy and regulation Katrina Brunton said.
"The container involved held 18 1000-litre containers of a highly flammable substance which also gives of a toxic gas.
"This gas could be smelled downwind from the container but not for a great distance.
"The pollution response team reported that the leak appeared to not be too large and the substance was in a gel-like form and appeared to be coming out the rear of the container."
She confirmed there had been no chemical discharge to waterways or the sea, and the spill was fully contained.
"The port had made sure a nearby drain was plugged to stop any runoff into the port and ocean."
A suction truck was also on standby, Brunton said.
The harbourmaster would later assess the vessel involved, she said.