Adib Khanafer has never run to surgery before, but he knew there was something different about the message he received on Friday afternoon.

The vascular surgeon was in an elective case at Christchurch Hospital when he received a call saying he was urgently needed in another theatre.

"This was a totally different call ... it said 'come now' and 'where are you' and 'how far'."

"This is the first time I have run to theatre," he told the Herald.

Khanafer didn't know it at that stage but nearly 50 people had just been shot dead at two Christchurch mosques. Dozens more were injured and flowing into the hospital in desperate need of help.

The majority were adult males but there were some women and a handful of children.

When Khanafer arrived in theatre he was confronted with an image he'll never forget - a 4-year-old girl with gunshot injuries who was fighting for her life.

She had been in surgery for about 45 minutes but his skills were now needed to help with vascular damage, especially around her pelvis.

"It was really sad to see a young girl on the table," he said, breaking down in tears.

Apologising for his display of emotion he went on to say he has four children aged 7-14.

"It could have been my boy, it could have been my girl."

Khanafer, who trained overseas, has worked on countless patients before, but never a child.

"The youngest in my career would be in their thirties, ninety per cent are above 60."

In surgery, he didn't stop to think about his wife, children or what had just happened in his home town. He didn't focus on the fact he was she was a child. He just put his emotions aside and did what he is trained to do.

The minute the surgery was done and the gown came off it was a different matter.

"I stepped out of theatre and started crying."

Afterwards, he called his family to check they were ok then went and spoke to the girl's father, who was also injured, to try and give him some reassurance.

"I said look, we have done our bit, the rest is up to God Almighty."

Khanafer, who was born in Kuwait and describes himself as a British Lebanese, said he has since leaned on his colleagues, friends and family for support.

While the saddest case, he also described the surgery as the highlight of his career and has been in touch with Starship Children's Hospital to check on the girl, who remains in a critical condition. Her father is also at Auckland Hospital.

"I am extremely optimistic," he said about her chances of recovery.

Khanafer said the horror of what happened had impacted on his children.

"My 13-year-old daughter wanted her mother to take off her hijab because she was worried she would be targeted."

However, the vascular surgeon remains positive about his hometown, despite the horror he has seen in theatre.

"I told her we continue to be in a safe town."

Twenty-nine people remain in Christchurch Hospital, 8 of whom are in a critical condition.