As survivors of the Christchurch mosque shootings recalled how elderly worshippers and children were mercilessly gunned down in New Zealand's worst massacre, a heroic tale emerged from Linwood Mosque, the second site where Muslim worshippers were shot dead.

At least seven people died at the Linwood Avenue mosque where an eyewitness, Syed Mazharuddin, said a man wearing body armour and a helmet opened fire.

“Just around the entrance door there were elderly people sitting there praying and he just started shooting at them,” he told the New Zealand Herald.

“There was a lady screaming and he shot her point blank in the face.”

Mazharuddin said a man wrestled a weapon off the attacker, who cut short his killing spree and ran to a waiting car.

“The young guy who usually takes care of the mosque ... he saw an opportunity and pounced on him (the gunman) and grabbed his gun,” Mazharuddin said.

“This guy, the hero, tried to chase but he couldn't find the trigger in the gun... he ran behind him but there were people waiting for (the shooter) in the car and he fled. “

'Very calm' gunman

About five kilometres away, Anwar Alsaleh was preparing for Friday prayers at the Masjid al Noor mosque in central Christchurch — where 41 victims were killed — when a gunman walked in.

Anwar hid in a bathroom and tried to call emergency services as shots rang out, telling stuff.co.nz he heard the gunman say an expletive about Muslims and “We're going to kill you today.” He said he heard people begging for their lives. “They shot them until they died,” he said.

The attacker live-streamed the attack, with footage showing him firing repeatedly at worshippers as he moved from room to room.

Witnesses at the Masjid al Noor mosque said the shooter was a white male with magazines of ammunition strapped to his legs.

One told Radio New Zealand the gunman was “very calm” during the rampage.

Mirwaiz, an Afghan refugee who did not want to provide his surname, said he came close to death when a bullet grazed his head.

“He started shooting at our side of the room and I lay down on the floor as a bullet grazed my head. A couple of centimetres lower and I would be dead,” he told stuff.co.nz, saying he fled from the mosque while the gunman's attention was elsewhere.

Others told of scrambling through broken windows and playing dead among the carnage in a bid to survive.

Carl Pomare was driving past the Masjid al Noor with an employee when he saw people running from the mosque and falling to the ground.

They pulled over and tried to help the injured, including a five-year-old girl.

“We managed to get her into the car of one of the people who was helping and got her to the hospital; she was critical,” he told RNZ.

“The guy that my worker was nursing, he passed away in his arms sadly. It was surreal.”