Authorities say they still have no idea what kind of fumes were released in a central Auckland building on Thursday, nor where they came from.
Emergency services were called back to level seven of Augusta House on Victoria St West on Wednesday night. Three people were taken to hospital and nine treated at the scene.
Twelve people had already been admitted in a leak earlier that day at the same property, suffering from shortness of breath, nausea and vomiting.
Fire and Emergency area commander Dave Woon said it's a mystery.
"There is obviously something wrong here, so we have to get to the bottom of it."
Building manager Heng Yue, the Auckland Regional Public Health Service and Worksafe are trying to find the cause of the fumes.
"We're going to have to look really seriously at what's going on here," said Mr Woon. "We've missed something."
The 16-storey building was closed overnight. All 15 people who were hospitalised are in a stable condition.
Newshub.
