Mr Brill said the phone call included threats of violence towards Work and Income staff.
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"Given the circumstances at present, police have taken precautionary measures and have closed the office."
A Rotorua police spokesperson said they were continuing to investigate the call.
"Police take very seriously any threats to MSD (Ministry of Social Development) staff.
"While some of these may be idle threats, police are taking action on each threat. In some cases, this includes shutting down sites until there is confidence that staff will be safe.
"MSD and police will continue to work closely together and MSD will refer each and every threat to police.
"People cannot and should not be able to threaten others without consequence."
Authorities have put in place 100 extra security staff at Work and Income offices around the country and beefed up a police presence in Christchurch since a spate of incidents following Monday's double homicide at Ashburton's Winz office.
Ashburton man Russell John Tully, 48, has been charged with two counts of murder and one of attempted murder over Monday's shooting.
A Rotorua Daily Post reporter outside Rotorua's Work and Income office said there was sign on the door and the office doors were locked. There were no staff members inside and police couldn't be seen.
No one in the area seemed to know what was going on, the reporter said.
A Ministry of Social Development spokesman told the Rotorua Daily Post they were aware of the lock down but had no further information at this stage.
A steady stream of people walked up to the door, read the sign and walked away.
A small crowd gathered outside, with people wondering when or if the doors would re-open.
While some were unconcerned - "more time to kill at The Warehouse" - others were annoyed and worried about missing appointments or not getting documents signed off.
One woman said she was there for her monthly appointment.
"I hope they don't cut my benefit off," she said.
She said threats and abuse towards staff had been going on for years.
"I have seen threats, people jumping the counter and getting frustrated," she said. "They need their money, times are hard."
Another woman, who was not a Work and Income client, said while there was no justification for the Ashburton shooting, she understood where the anger and frustration came from.
Meanwhile, police investigating a threat that shut down all Work and Income offices in Canterbury this morning say they have spoken to the alleged suspect and concluded there is no threat to staff.
The Ministry of Social Development closed all Canterbury sites as a precautionary measure after being made aware of a verbal threat against Housing New Zealand staff in Christchurch.
In Thames, a man has been charged following an incident in the Thames Work and Income office today.
Acting Senior Sergeant Martyn Hughes of the Thames Coromandel said police were called to the Community Link Office on Pollen St shortly after 10.30am.
"A disgruntled customer allegedly made insulting remarks with reference to Monday's events in Ashburton."
"As a result the 22-year-old man was arrested and will appear later today in the Thames District Court on a charge of using insulting language in a public place."
Mr Hughes said it was hoped the charge would reassure the community police took all such incidents seriously.
"People cannot and should not be able to threaten or insult others without consequence and our top priority is to ensure the safety of all members of the public."
A 38-year-old man was also arrested following a threatening phone call made to Work and Income staff in Blenheim yesterday morning.