The five seriously injured people were taken to hospitals, police said.
Media reports said all of the victims were construction workers.
The 100-metre overhead bridge was to connect a parking lot with the main Jawaharlal Nehru Stadium, which is to host opening and closing ceremonies as well as showpiece athletic events for the October 3-14 games.
An AFP reporter at the scene said police had sealed off the area and heavy lifting equipment had begun shifting sections of the footbridge which had fallen down onto the car park tarmac below.
A giant steel arch over the bridge was still standing, but load-bearing metal cables that had previously held up the overpass had snapped and could be seen dangling in the air.
“The cementing of the footbridge was being done in the morning,” chief secretary of Delhi Rakesh Mehta told CNN-IBN television. “The engineers are looking into the cause of the accident.”
Severe delays in the completion of the athletes’ village have thrown the sporting event into jeopardy.
The collapse came as the Commonwealth Games Federation went public with complaints about the athletes’ village, which was described as “filthy”, “uninhabitable” and “not fit for humans” by participants and officials.
New Zealand, Canada, Scotland and Ireland have described the accommodations as “unlivable,” and the New Zealand delegation said on Tuesday the village won’t be ready for its official opening this week.
New Zealand team manager Dave Currie told radio network newstalkZB that New Delhi organisers “are in severe difficulties,” identifying problems with cleanliness, plumbing, electrical wiring, internet access and mobile phone coverage.
Construction work for the games, expected to draw 7,000 athletes and officials to the Indian capital, has been severely delayed and doubts have been raised about the quality of the construction.
India’s chief anti-corruption body found a host of problems with construction work in a July investigation, including dubious contracts and the use of poor quality materials.
The chief technical examiner from the Central Vigilance Commission (CVC) inspected 15 sites around the national capital and found a number of irregularities and suspect practices by contractors and public bodies. The official price tag for the games is $US3 billion ($A3.17 billion) - about five times the original figure.
Commonwealth Games will be held in Delhi October 3-14, 2010. The shooting of two men on a tourist bus and the collapse of a new footbridge injuring more than 20 people are not good signs for Commonwealth Games organizers and India.
Athletes from Australia and the United Kingdom have already pulled out of the Games. NZ is also planning on same issues. Federal Sports Minister Mark Arbib said “We are concerned and we are seeking more information from the High Commission and asking them to have discussions with their Indian counterparts.” New Zealand Prime Minister John Key said “I would support any athlete who decides not to participate in the Commonwealth Games . They have to make their own decision on whether they feel comfortable or not with the risks involved”.
Key also said “If the Commonwealth Games did not go ahead that would have significant implications for the future of the Commonwealth Games and that’s not something we’d like to see and it also wouldn’t be good for India.”