Wellington-based New Zealand American Association chairman Larry Keim is appalled by the shootings and says the United States' gun laws must be tightened up.
"When will it stop," Mr Keim said of mass shootings in the United States.
"It's what happens when in the early 90s, suddenly guns become more prolific, especially those that have large magazines. The Second Amendment [of the Constitution] has been taken to a whole new perspective."
"The NRA [National Rifle Association] has a strong lobby. It's something Congress refuses to deal with."
Mr Keim said he hoped President Barack Obama could address this "in a much stronger fashion" in the last year of his presidency.
"I don't have a problem with the Second Amendment right to bear arms. What I do have a problem with - I grew up in California and we went deer hunting with a rifle and target shooting - we didn't have all these militarised weapons, semi-automatics meant for killing people.
"When I was growing up it was a bolt-action rifle.
"Why does someone need to own a machine gun?"
A US passport holder and New Zealand permanent resident who has lived here for 10 years, Mr Keim said the US must adopt tighter restrictions on what guns people can have and who can have them.
Mr Keim said he would call his brother who lives in California some distance from San Bernardino.
"I've got to find out what is going on with him."
John Drucker, of the American Club, Auckland, said: "It is too early to know if any of our American Club members have anyone directly or indirectly affected by the shootings in San Bernardino until we receive more detailed information on this unfortunate tragedy."