The Ministry of Social Development has acknowledged it did not take all possible steps to protect staff at its Ashburton office.
The ministry has been convicted of breaching workplace safety legislation after the fatal shooting of two staff members at the office.
Leigh Cleveland and Peggy Noble were killed by Russell Tully in September 2014 and a third staff member was wounded.
MSD chief executive Brendan Boyle said the ministry should have had a zero tolerance approach to threatening and abusive behaviour, and it did not.
"The fact is that all around the country we had staff who were putting up with behaviour that was completely unacceptable," he told Morning Report.
In sentencing notes released yesterday, Chief District Court Judge, said the ministry's own data reporting system recorded 31 moderate and serious incidents at the Ashburton office between 2008 and 2014.
She referred to emotional distress experienced by the organisation's staff before the shootings, as revealed in victim statements made to the court.
"They paint a picture of staff who felt distressed and under-supported when confronted by violent clients. Staff experienced feelings of anxiety and that they were expected to simply 'put up' with abusive behaviour.
"Staff felt anxious, apprehensive, intimated, scared, tense, nervous, uncomfortable or exposed and exhausted by the lack of physical protection and responsiveness of the defendant. In short, they felt vulnerable."
Mr Boyle said work on improving security was happening before the events in Ashburton and it was accelerated afterwards.
"As we move forward and put the legal aspects of the tragedy behind us, we will continue to make sure we do everything we can to keep our staff and our clients safe."
MSD convicted, but no penalty
Though the ministry was convicted, no further penalty was been imposed.
Judge Doogue said legally no fine could be imposed in the case because the defendant was a Crown organisation.
The prosecution was taken by WorkSafe at a cost of $258,000. The health and safety regulator did not do a cost analysis for the case.
"The fact we weren't able to have a fine laid down is not a major issue," said WorkSafe chief investigator Keith Stewart.
"We believe it was important to take the case to get some accountability and clear guidance for the future."
Public Service Association's national secretary Glenn Barclay said front line public servants often bore the brunt of clients' frustrations.
"The ministry has learned a number of lessons from this, as well as other agencies," he said.
"They deal with people with a number issues who can be very challenging. Verbal abuse, for instance, can be very difficult for staff."
The PSA had been working with the ministry in establishing new guidelines for office layouts.
The State Services Commission said it was "leading work across government, including with WorkSafe and MSD, to respond to the judgement and its implications".
"This work will develop guidance for government agencies to help them consider and manage risks in their customer service areas while they make sure their service centres remain welcoming places for all New Zealanders," it said.