Work and Income offices will be locked down in the event of future threats.
Security guards will control entry to sites and may demand proof of identity following this week's Ashburton shooting.
Cabinet minister Paula Bennett gave an update of a security review with Ministry of Social Development chief executive Brendan Boyle in Wellington this morning.
Peggy Noble, 67, and Susan Leigh Cleveland, 55, were killed at their Cass Street office on Monday.
Bennett said the incident has brought out the best in people, as well as the worst. There would now be zero tolerance of threats and abuse of staff even if it meant people could not access help, she said.
"We have taken those threats seriously. The message that we are sending out is that we have zero tolerance for any threats or even abuse on staff and we will be acting appropriately.
"In some circumstances that will mean us locking down sites that means other people that genuinely need help are not able to get it as quickly or as efficiently as they require it. But those are the steps that we are well prepared to take if we need to."
Boyle said that from next week security guards will control entry and may ask for ID.
"If anyone is identified as presenting a risk they may be refused entry. While that may cause some slight inconvenience to clients we believe that in the interests of safety for both staff and clients this is a step that is important to take."
He added: "We have multiple channels that people can access. It's not just face to face. We have a contact centre ... clients will still have access to those sites but in a more controlled manner."
There are currently security guards at every office and an 108 extra staff were added in the last few days. Some sites now have two and three guards where threats have been made, Bennett said.
Work and Income staff have "quite a high threshold for abuse", she said. "They are saying 'is it too high? Are we putting up with too much inappropriate behaviour?' And it would be my impression that they are.
"So we are saying that actually we won't tolerate it. If you are starting to get abusive you'll be asked to leave and come back when you have calmed down. And if necessary you'll be trespassed and call the police. Safety is absolutely paramount."
Boyle agreed an incident like the shooting could "arguably" not be prevented. "That's part of what we will look at in the security review. We've always been at the risk of a lone gunman just as any organisation. It could be a bank, it could a local diary so that's a risk that's very, very hard to plan."
Former police commissioner Robbie Robinson would head the independent review into security protocols with Deloitte boss Murray Jack, Boyle said.
It would be supported by an advisory group led by former Department of Prime Minister and Cabinet boss Sir Maarten Weavers. They would also be able to consult with security experts.
They would look at whether all practical steps were taken to ensure the safety of staff and what physical security changes are required in MSD workplaces.
The review would take place in two parts, with the first part into Work and Income sites completed in two weeks. The second part, which would take longer, would look at other ministry sites.
Bennett said MSD was doing everything it could to support the families of Noble and Cleveland. Boyle has also talked with Lindy Louise Curtis who survived the shooting.
"We have a long way to go. This is not a quick healing for anyone but we are going to do whatever it takes for the duration of time that we need to help all of our staff through this."
No decision has been made on when the Ashburton office would open, but MSD was looking at bringing staff from other areas into the region.