Almost a dozen shooting victims, including two boys, have undergone surgeries overnight after doctors from across New Zealand headed to Christchurch after a mass shooting at two Muslim mosques on Friday.

Christchurch Hospital’s Chief of Surgery Greg Robertson spoke to reporters on Saturday, revealing the youngest victim to survive the shooting spree was aged just two years old, the other boy aged 13.

Both are in a stable condition.

Dr Robertson said 12 operating theatres worked overnight at the city’s main teaching hospital where 11 patients remain in the intensive care unit in a critical condition including one woman aged in her 20s.

“Of the 48 patients admitted to Christchurch Hospital from the incident, seven have been discharged. The others include a 4-year-old girl who has been transferred to the Starship Hospital in Auckland in a critical condition.

“Four patients died on their way into the hospital yesterday, dying before they arrived.”

A total of 39 patients remain in hospital.

There are grave fears the death toll may rise. It currently stands at 49 dead.

“They [the injuries] range from soft tissue injuries to more complex injuries involving the chest, abdomen, pelvis, long bones and the head. Many of the people will require multiple trips to theatre to deal with the complex series of injuries that they have,” Dr Robertson said.

The death toll may rise as 11 shooting victims are still in a critical condition. Photo: Getty

New Zealand St John Ambulance chief executive Peter Bradley said: “I couldn’t be prouder of the way that my call-takers, dispatchers and ambulance crews [worked] yesterday in what was an horrific situation”.

“Their ability to triage, treat and transport so many patients so quickly and effectively saved lies,” he told reporters on Saturday.

A New Zealand fundraising page, the Spark Foundation, has already raised $1.5 million from 25,000 donations to support victims directly affected by Friday’s massacre.

Meanwhile, hundreds of people grief-stricken and shocked after the massacre have made their way to memorials across the world to pay tribute to the 49 people who lost their lives in the shootings.

A rally will be held in Melbourne on Saturday in a bid to “stand together against Islamaphobia”.

The rally will be held at Victoria’s State Library, with a prayer from Imam Alaa Al-Zokm from Victoria’s Muslim community, alongside Mohammad Helmy, the secretary of the Islamic Council of Victoria, and other anti-Islamophobia activists.

The rally is one of many protests of its kind held around the world ahead of next week’s International Day for the Elimination of Discrimination.

A number of Melbourne’s landmarks were lit up overnight in the New Zealand flag colours in a show of solidarity, including Flinders Street Station, the Town Hall and the State Library.