An estimated 2000 to 2500 people were at Te Papa last Saturday at the same time an Australian traveller who later tested positive for Covid-19 visited, the museum said today.
The museum is among more than a dozen exposure sites identified across Wellington that the case visited, including a pharmacy, a supermarket, a bookstore, and several restaurants.
The Ministry of Health said people who visited Te Papa’s Surrealist Art exhibition between 4pm and 5.45pm on Saturday June 19 must self-isolate for 14 days because they're considered close contacts.
Those elsewhere at the museum between 3.05pm and 5.45pm on that same day have also been asked to stay at home and get a test around day five after their last potential exposure to the case, or if they develop symptoms. They are required to stay at home until they return a negative test result.
Te Papa said it would remain closed for the rest of today and tomorrow for deep cleaning. It is expected to provide an update tomorrow about whether it will open on Friday and the weekend.
The museum’s chief executive Courtney Johnston is among those considered close contacts as she was at the exhibition on Saturday. She is self-isolating and working from home.
She told 1 NEWS the main concern at the moment was making sure staff and visitors were safe.
"It was a very, very busy weekend. So, we do realise this is a sizable thing that we're dealing with here."
Johnston said she still wasn't sure how many staff may be considered close or casual contacts, or how many staff were in the building on Saturday.
"We had a lot of staff in the building and in different parts doing different work. But then, of course, they cross paths. We're working through those intricacies ... we're reaching out to everyone and then all our information will be handed back to the Ministry of Health."
The museum was also in the process of working out how many staff it needed in the coming days, and whether they would have enough to re-open once it was safe, she said.
Earlier today, there was some confusion among locals and tourists about whether the national museum was open or not.
Despite a tweet shared at about 9.30am announcing its closure, it wasn't until later on in the morning that Te Papa had put up a sign about the Covid-19 case.
Several people have told 1 NEWS they were disappointed and Te Papa's communication needed to improve.
One father, who was planning to visit the museum with his family, said a staff member had said Te Papa was open over the phone.
Johnston said the museum accepted it had "dropped the ball in terms of getting a sign up at the door", but that security staff were at the entrance to tell people they were closed.
"This is the first time we've done this precise protocol, so there's always going to be something you can learn from doing it. We do our best in the time, with the information that we have available.
"At the end of that, we look at it and we go, 'okay, how do we do better next time?'"
Stuff reported two conferences, a National Emergency Management Agency meeting and T-Tech 21, were set to be held at the national museum this morning. Both ended abruptly once Te Papa was identified as a location of interest.
Johnston confirmed there were two conferences at Te Papa this morning.
She said Te Papa learnt it was a location of interest this morning when the information was made public by the Ministry of Health at about 8.55am. By the time the decision was made to shut the museum, the conferences had already gotten underway. Te Papa staff then told them they had to stop and leave the premises.
"We made the decision to close pretty much straight after the information was released online," Johnston said.
This afternoon, Covid-19 Response Minister Chris Hipkins said he was first told about the traveller from Sydney between 7.30pm and 8pm yesterday.
Hipkins said information was released publicly as soon as it was available, with New Zealand health authorities speaking to the traveller in the early hours of this morning.
When asked whether she wished she was told earlier about being a location of interest, Johnston said: "I realised information is released as soon as can be. We're all in the same place here.
"I don't particularly wish for a special heads up, I think everyone's doing the best they can in the circumstances."
However, some have criticised the Government for being too slow with information, including National leader Judith Collins and ACT leader David Seymour.
News of the traveller broke shortly before midnight yesterday, after a tweet from NSW Health.
Full details and advice on locations and times of interest can be found on the Ministry of Health’s website.
The Wellington region moved to Covid-19 Alert Level 2 at 6pm today. The rest of New Zealand remains at Alert Level 1.