CHRISTCHURCH (Reuters) - New Zealand rescue teams worked under search lights early Wednesday to find scores of people trapped under collapsed buildings after an earthquake struck the countrys second-biggest city of Christchurch, killing at least 65 people. About 120 survivors have already been rescued from the rubble, but the death toll is expected to rise following the second strong quake to hit the city of almost 400,000 people in five months. We may well be witnessing New Zealands darkest day...The death toll I have at the moment is 65 and that may rise, said New Zealand Prime Minister John Key, who had flown to his home town of Christchurch, where he still has family. Tuesdays 6.3 magnitude quake struck at lunchtime, when streets and shops thronged with people and offices were still occupied. It was New Zealands most deadly natural disaster for 80 years. Rescuers, working under lights in rain, focussed on two collapsed buildings: a financial-services office block whose four stories pancaked on top of each other, and a TV building which also housed an English-language school. About a dozen Japanese students at the school were believed to be missing, an official in Japan told Reuters, while public broadcaster NHK said several other students from another group in the building were also unaccounted for. Trapped survivors could be heard shouting out to rescuers from the TV building. Local media say as many as a dozen or more people could still be inside. Relatives of those feared trapped kept a vigil outside the building as rain began to fall. All of our energy tonight is really focussed on the need to rescue people, said Christchurch Mayor Bob Parker, estimating 120 people had been pulled out of rubble or rescued so far. A woman freed from a collapsed building said she had waited for six hours for rescuers to reach her after the quake, which was followed by at least 20 aftershocks. I thought the best place was under the desk but the ceiling collapsed on top, I cant move and Im just terrified, office worker Anne Voss told TV3 news by mobile phone. Christchurch Mayor Parker described the city, a historic tourist town popular with overseas students, as a war zone. He told local radio that up to 200 could be trapped in buildings but later revised that estimate down to around 100 or so. It was the countrys worst natural disaster since a 1931 quake in the North Island city of Napier which killed 256. Christchurch Hospital saw an influx of injured residents. They are largely crushes and cuts types of injuries and chest pain as well, said David Meates, head of the Canterbury Health Board. Some of the more seriously injured could be evacuated to other cities, he added. On the way into the city, a Reuters correspondent saw buckled roads, toppled buildings and big pools of water. Police and the army were patrolling the streets. Christchurch has been described as a little piece of England. Emergency shelters had also been set up in local schools and at a race course. Helicopters dumped water to try to douse a fire in one tall office building, while a crane was used to help workers trapped in another office block.