Five people were killed and another 15 injured when a section of a partially-constructed New Delhi metro bridge gave way suddenly early Sunday, a spokesman for the rail service said. The accident occurred when a pillar supporting part of the carriageway collapsed, Anuj Dayal, spokesman for the Delhi Metro Rail Corporation (DMRC) told reporters. "We are investigating the matter. It appears that there is a problem in the design of the pillar of the bridge," Dayal said. The dead were labourers who were among a group of 30 men working at the site in south Delhi. While three of the five were pronounced dead in hospital, emergency workers were still trying to recover the bodies of two others from the concrete debris, Dayal said. "Two of the injured are in a serious condition" while some workers had been discharged after first aid, he said. Television footage showed a long section of concrete lying at an angle with one end on the ground and the other atop a supporting pillar. DMRC chief E. Sreedharan, who toured the site, later told reporters he had submitted his resignation to the Delhi government, taking responsibility for the accident. "In this project we have maintained a fairly high standard of safety. Today is a major jolt. "I personally feel I have to take full moral responsibility for this accident... I have decided to resign as managing director of DMRC," Sreedharan said after naming a five-member committee to investigate the collapse. The New Delhi metro system, launched in 2002, has been lauded for its cleanliness and efficiency and has revolutionised travel in the Indian capital with 14 million people and more than 3.2 million vehicles. The metro has several lines covering about 75 kilometres (47 miles) and authorities are hoping to complete several extensions in time for the October 2010 Commonwealth Games. Sunday's accident is the second major incident involving the Delhi metro in less than a year. In October, two people were crushed to death and 12 injured when a bridge being built to extend the metro system collapsed onto a bus and cars. Keep up with the latest business news from the region with the daily Emirates Business 24|7 newsletter. To subscribe to the newsletter, please click here .