UPDATE: A Waihi Beach woman is currently undergoing surgery in a hospital in Australia after being shot in the leg by a stray bullet in Papua New Guinea.

Cathy Franzoi, a 40-year-old volunteer ambulance officer, was shot in a gun battle on Sunday during a volunteer trip with her 15-year-old son Luke.

Rodney and Cathy Franzoi. Photo: Facebook.

Speaking to SunLive from the couple's Waihi Beach home, husband Rodney Franzoi says Cathy is undergoing surgery on her right leg in Cairns and he's waiting to hear how it went.

Luke is now at home with Rodney and his three brothers, Benjamin, Ethan and Joel.

"We're all good and she's in Cairns. I'm not worried about her there, I was worried when she was in PNG, medically," says Rodney.

He says when his wife called him to say what had happened it took a lot of convincing for him to believe her.

"I thought she was kidding, because she rung me. If someone else had rung I would have been more concerned, but she called and said 'Don't worry, it's all good but I've been shot'.

"And I was like ‘Yeah right'. She thought it was funny."

He says the memorable phone called was "strange and surreal".

"If you can't be somewhere you only have two ways to respond. You can panic and go crazy, or you can go what can I do from this far. And we did what we could."

Cathy had finished a duty with the Ywam Medical Ships on Sunday morning when she was shot in Port Moresby.

He believes it won't put his wife off any future volunteer work, and says now she has a solid battle story to brag about.

Rodney has been the Waihi Beach Christian Camp manager since 2011.

It is understoof Ywam's ship the M/V Pacific Link has on-board facilities offering simple treatment of infection to life changing cataract surgeries.

A Ministry of Foreign Affairs spokesperson says the incident is being investigated.