NEW DELHI, India (CNN) -- A portion of a partially built bridge for New Delhi's metro rail network collapsed Sunday, killing five people and injuring 15, authorities said.
The crash occurred when a metal beam supporting pillars gave way, Delhi Metro Rail Corp. spokesman Anuj Dayal told CNN.
Concrete slabs came crashing down, burying workers beneath, officials said.
The dead included one site engineer, said Mohammad Akhlaque, police sub-inspector.
The man in charge of building the Metro system offered to quit the project Sunday.
"I take full moral responsibility for this accident. And having taken this moral responsibility, I have decided to resign as the managing director of Delhi Metro Rail Corporation," Elattuvalapil Sreedharan told a news conference.
Sreedharan, 77, however, noted that Sunday's crash would set the metro project back by three months.
New Delhi launched its metro system six years ago, a project that cut through India's bureaucratic red-tape that usually holds back big infrastructure programs.
Construction on new lines has been proceeding at a frenzied pace as the city gets ready to host the Commonwealth Games in 2010.
Hailed as a relief in India's traffic-congested capital, the metro has a tarnished safety record.
Part of a another bridge being built to extend the rail system collapsed last October, pinning a bus underneath and killing its driver.