( CNN ) -- A 6.3-magnitude earthquake ripped through Christchurch , New Zealand , on Tuesday afternoon , causing multiple fatalities as it toppled buildings onto buses , buckled streets and damaged cathedrals , authorities said . New Zealand Police announced on the agency 's website that a large-scale evacuation of the central city was under way . According to the news release , the earthquake killed an undetermined number of people at various locations around the city , including passengers on two buses crushed by buildings that had fallen on them . TVNZ reported that the 147-year-old Christchurch Cathedral 's spire had toppled , Christchurch Hospital was being evacuated and the airport was closed . Laura Campbell told CNN she was at work at the bottom of a six-story building when the earthquake struck . She described seeing `` windows blowing out , bricks falling down , people screaming , the whole nine yards . '' `` It was bloody serious , '' said Campbell , who was trying to walk home . `` I 'm worried about what I 'm going to find down the road . '' The U.S. Geological Survey said the quake struck just before 1 p.m. Tuesday ( 7 p.m. Monday ET ) , and a 5.6-magnitude aftershock struck about 15 minutes later . The U.S.G.S . recorded a second 5.5-magnitude aftershock shortly before 3 p.m. local time . The New Zealand Herald reported that phone lines in the area were out , including the city 's emergency 111 service , roads were cracked -- in some cases lifted as much as a meter ( 1 yard ) -- and water mains had burst , flooding several streets . Witness Philip Gregan said he was attending a joint U.S.- New Zealand conference when the earthquake struck . `` I 'm seeing a lot of damage in buildings , there are glass and bricks in the road . I 've seen one collapsed bridge and there 's a lot of water from broken water mains , '' he told CNN . `` I saw one ( injured ) person in the back of a police car and one of our colleagues saw a person crushed by falling debris , so there are definitely dead . '' New Zealand 's transit authority told TVNZ that it had been unable to reach its staff in Christchurch and at the Lyttleton Tunnel , which is near the epicenter . Christchurch police told TVNZ that the city 's 106-year-old Cathedral of the Blessed Sacrament was badly damaged , and a Herald reporter said that half the building had collapsed . Camera footage aired by the station showed piles of stone lying atop crushed chairs on the floor of the cathedral with light shining through the collapsed tower above the sanctuary . Witness Gavin Blowman told CNN how he ran into the street when the earthquake struck . `` It felt like I was running on jelly , '' he said . `` We saw a giant rock tumble to the ground from a cliff -- a rock that had been there for millennia . It fell on the RSA ( Returned Services Association , a veterans ' association ) building -- it was terrifying . '' He said there were now fears that a tsunami could hit in the wake of the quake and that he and 20 other people were trying to get to higher ground . Flying out of the city currently was not an option in the hours immediately after the quake . `` The airport is currently closed until further notice , '' an airport employee told CNN some two hours after the quake . All planes inbound for the airport were being diverted , and no planes were allowed to take off . No one was injured at the airport , he said . The employee did not give his name and wanted to clear the phone line to continue emergency work . The quake caused significant damage to several older buildings , a Herald reporter said . New Zealand Prime Minister John Key said he would attend an emergency Cabinet meeting in Wellington and then fly to Christchurch if conditions allow . Christchurch Mayor Bob Parker told Radio New Zealand that the rumbling tossed him across the room , that he knew of injuries in the city council building and has heard unconfirmed reports of serious injuries . `` That was , in the city central anyway , as violent as the one that happened on the 4th of September , '' he said . Parker added that streets were jammed as people tried to get out of the city , and he urged people to avoid the water supply . `` We 've been through this before this once , we now need to think what we did at that time , '' he said . Southern New Zealand has been plagued by a series of quakes since September , when the area was shaken by a 7.1-magnitude temblor that New Zealand authorities said was the most damaging quake to hit the region since 1931 . The earthquake struck in the predawn hours of September 4 . Authorities said the deserted streets at that time likely kept injuries to a minimum . There were no deaths from that earthquake . Both the Roman Catholic Cathedral of the Blessed Sacrament and the Anglican Christchurch Cathedral were undergoing repairs after being badly damaged by the September quake . The quake struck in the `` worst possible location , '' Kevin Fenaughty , data center manager for GNS Science , told the Herald . `` It 's a nightmare , '' he said . `` A lot of people were just getting back on their feet after the original quake . '' TVNZ also reported that its newsroom in Christchurch was badly damaged .
NEW : Police say the 6.3-magnitude earthquake caused ` ` multiple injuries '' NEW : Large - scale evacuations of central Christchurch are under way . Christchurch : Witness ##es ` ` windows blowing out , bricks falling down , people screaming '' The city 's Catholic and Anglican churches are damaged ; Christchurch airport is closed .