A man has been taken into custody after a "family harm incident" that turned into a billowing blaze in Whangarei.
Emergency services were called to a property on Maunu Rd about 6.30pm.
Police told the Herald they were initially called to a family harm incident where a woman had been kept hostage.
"When police got to the scene the property was on fire. Reports of a woman being kept hostage were inaccurate," a police spokeswoman said.
Police were speaking to the man and other people who were at the property to establish what happened.
Earlier in the night, a witness told the Herald residents were being warned to lock themselves inside their homes because someone was running around with a knife.
Police could not confirm whether the man was armed.
The witness, a resident of the street, told the Herald the scene was swarming with police, Armed Offenders Squad officers and police dog teams.
"Police told everyone to lock themselves inside because someone is running around with a knife.
"They said get inside."
A search of the fire-affected property had been undertaken and it was believed all the occupants of the house got out safely, a police spokesman said.
The man in custody, who was involved in the family harm incident, was caught after fleeing the scene on foot, the spokesman said.
Maunu Rd was closed between Western Hills Dr and Hospital Rd, while emergency services worked at the scene of the fire.
The fire is now out and Fire and Emergency New Zealand's investigative team will be returning to the scene tomorrow to determine the cause.
"There's a lot of damage. It's pretty well destroyed," a FENZ spokesman said.
The resident said flames were leaping into the air with "really black smoke" from an old bungalow-style house.