Medics in the city of Christchurch are trying to “comprehend the incomprehensible” as they continue to treat the dozens of people wounded during the New Zealand mosque attacks.

A total of 50 people were killed in the shootings at two mosques during Friday prayers, while another 50 were injured.

Thirty-four people remain in Christchurch Hospital, 12 of them in intensive care, while a four-year-old girl is fighting for her life at a hospital in Auckland.

Greg Robertson, chief of surgery at Christchurch Hospital, described how victims were brought to the hospital in cars as well as ambulances as the horror unfolded on the streets of an otherwise peaceful city.

Asked how staff felt as the scale of the attacks became apparent, Mr Robertson added: “Horror. Stunned. Anger.”

Doctors battled with complex gun shot injuries and surgeons worked through the night to save the lives of victims who ranged in age from children to the elderly.

“Those who got here (to hospital) had a chance,” said Mr Robertson.

But as the atrocity sent shockwaves across the world, those on the front line were left to come to terms with the reality of what they had encountered.

“It’s a bit challenging for people – we are all part of the community and we’re struggling with it as much as anyone else,” said Mr Robertson.

“This is not something that we expected to see in our environment.

“We do see gunshot wounds, but 40, 50 people in a day is more than we should see.”

Mourners lay flowers on a wall at the Botanical Gardens in Christchurch
Mourners lay flowers on a wall at the Botanical Gardens in Christchurch (AP Photo/Vincent Thian)

“Most people cope with things pretty well when you’re doing things,” he added.

“It’s when you go home and you think about it that that’s when the issues start to declare themselves.”

The magnitude of the attacks will have an impact on hospital staff for a long time to come, said Mr Robertson.

“It’s just comprehending what is incomprehensible”, he said.

“People will wonder if they could have done better, if there are things they could have done differently.”

While a terror attack of this scale is unprecedented in New Zealand, medics in Christchurch have experience of dealing with mass casualties following an earthquake in 2011 which killed 185 people.

Mourners pay their respects at a makeshift memorial near the Masjid Al Noor mosque in Christchurch
Mourners pay their respects at a makeshift memorial near the Masjid Al Noor mosque in Christchurch (AP Photo/Vincent Yu)

But this was a different kind of tragedy.

“People had got their heads around the earthquake, it was something we couldn’t control,” he said.

“This… it’s that fact that someone has done this to our people, our friends, our colleagues, that is just unbelievable.”