A family lawyer has been taken to hospital with serious injuries after disorder in the Whangārei courthouse.
The lawyer was injured in the lift.
Inside the building on Thursday morning, police were present and the lift was taped off.
There was an 'out of order' sign on it and a cleaning bucket alongside it.
Emergency services were called just before 10am.
St John said a patient had been taken to Whangārei Hospital via an ambulance.
A police spokesperson said one person was taken into custody but there was no wider risk to the public.
Ministry of Justice chief operating officer Carl Crafar said the alleged offender was immediately detained by court security officers and was then arrested by police.
"The court was briefly locked down as a result of the incident, and has now re-opened."
Law Society family law chair Caroline Hickman said the attack was "horrendous" and "incredibly distressing".
Hickman told RNZ barristers from around the country had been making contact since the incident, sharing concerns.
"It makes family lawyers feel very vulnerable, because we're already dealing with people in heightened emotional states. So it's part of our role that we do have to de-escalate people from conflict at times, but you certainly don't expect to be physically attacked.
"It's really unsettling for family lawyers to hear about."
New Zealand needed "more family lawyers than ever, there's a real shortage around the country - it's because it's a hard area of law to work in", Hickman said.
"Family lawyers have chosen that area of work because they really want to help people. And they want to help people who are at often the lowest point in their lives.
"So the people who are really in crisis, often, people who really have heightened emotions, and if it's about their kids, often, it's really incredibly sensitive, and for them an incredibly sad time.
"But it does mean that sometimes you're dealing with people who are really very volatile, and you have to work hard to try and help de-escalate things and calm things down."
When asked if she had ever felt threatened in her work, Hickman said: "I'd be surprised if there was any family lawyer who hasn't felt unnerved at times when dealing with someone in an acutely heightened emotional state, where they appear threatening or threatening towards you.
"Unfortunately, it's something that does happen in our profession. And it can be extremely stressful.
"We don't ever want this to happen again," Hickman said, adding that lawyers she had spoken to agreed.
"We understand that the Ministry of Justice will be looking at reviewing the situation to see if there's anything that they could be doing differently regarding the spaces.
"But we have security guards, we have searching when we go into courts ... We do appreciate that there is really good security checks at court. You go and you get screened."
Catherine Cull KC has practised family and criminal law in Te Tai Tokerau for more than 20 years.
She told RNZ Thursday's assault was one of the most extreme acts of aggression against a lawyer she had heard of in years.
"Judge Augusta Wallace, she was macheted inside the court. But that was 30-ish years ago. I know of another lawyer who was beaten up in the cells by his client, and severely injured."
Lawyers around the region were "shaken" and she had had texts all day checking whether she was okay, Cull said.
"The other thing is our families who will see this in the news ... When they see us go out the gate every morning, they're going to be worried. So it's got a big trickle-down effect."
Lawyers working at courts these days had to have "eyes in the back of their heads" to watch out for agitation from clients, she said.
"Families that you're dealing with them, they're at the lowest [point] of the low. You know, sometimes they just they act in a way without thinking potentially or they get pissed off with what's happening. And you are frontline. You are the one that is gonna cop it."
It was impossible for court security to be everywhere at once - particularly in multi-storey courthouses like Whangārei, she said.
"It's quite a rabbit warren. So if you had to make an emergency exit, if you like, you would still have to go through the foyer or down the stairs or in the lift. There's no actual direct private access for counsel."