"She realised she was shot and rolled on to the floor."
Mrs Franzoi was flown to a hospital in Cairns, Australia, on Monday for treatment. She was in a stable condition, and preparing for surgery yesterday.
Speaking from his home in Waihi, Mr Franzoi said he initially thought his wife was joking when she contacted him to break the news.
She told him: "Don't panic but there has been an accident ... I've been shot."
But he soon realised that she was serious and was concerned because she was so far from home.
X-rays and CT scans showed his wife had no neurological or nerve damage to her leg.
"The bullet hasn't fragmented, that would have been one of the problems. But I've told her to bring it [the bullet] home with her," he said.
Their son Luke arrived home yesterday. He had slept through the shooting.
"Someone woke him up saying, 'Your mum needs to talk to you'. So he went into her room and there she was with a bullet in her leg," Mr Franzoi said.
The couple have lived at Waihi Beach for three years after emigrating from South Africa, where they worked as paramedics.
"There are so many times that I could have been shot over there and I wasn't - and then this happens to her."
He said the incident had not stopped the family's willingness to help on other missions.
YWAM said it was sad to confirm one of its volunteers had been injured.
"The incident occurred after she had completed a project serving on our medical ship helping local people in Papua New Guinea's Gulf Province with medical training and community development needs, while awaiting her return flight to New Zealand.
"Our thoughts are very much with Cathy and her family, and our priority remains to do whatever we are able to speed her recovery."
It was the first incident of its kind in more than 22 years, the non-profit organisation said. A thorough investigation would be conducted to see if there was anything it could do to improve safety for its volunteers.
Mrs Franzoi had been travelling with members of the Waihi Baptist Church, said community pastor Alan Scott, who was also on the trip.
"Each member of the team has had a memorable time in PNG and is determined that a single event will not overshadow the amazing experience and all are keen to return on another occasion."
The Ministry of Foreign Affairs and Trade said it was aware of Mrs Franzoi's situation and had offered consular support.