Emergency services donned protective clothing before entering the Havelock North PostShop.
A postal worker got a shock when white powder fell out of a parcel she was sorting.
Emergency services descended on Havelock North this morning after staff raised the alarm at the package.
Part of the village was cordoned off and staff from the Post shop and adjoining Unichem were evacuated.
Fire staff donned protective clothing before entering the building.
New Zealand Post worker Robyn Bedford was sorting the mail when she discovered the powder.
As is protocol, she told her manager who alerted the emergency services.
Ms Bedford came into contact with the powder so was kept away from other staff while fire crews investigated.
"Yes, that's why I'm on this side of the tracks, I'm not allowed over with the girls," she said.
She said she felt fine about the incident and would be put under the shower if needed.
Hawke's Bay Area Commander Ken Cooper said fire crews were called to the post shop on Napier Rd just after 9am as an unknown substance spilled out of a package.
His staff contained the scene until the substance could be identified.
"While it's an unknown substance we can't take any risks with public safety so we're erring on the side of caution until we can identify the product."
When it was, it was found to be a non hazardous cooking material.
Mr Cooper said such callouts were rare and it was good practice for fire crews working together with police and council staff.
The cordon has now been taken down.
Javon Aranui was rushed to hospital in an ambulance but died the next day.