Helicopters fished the two victims from the water and laid them out on São Conrado beach, where a crowd of beachgoers gathered around them.

The accident came just hours after the Olympic flame was lit in Greece, at the start of a 15-week journey that will culminate with the 5 August opening ceremony in Rio de Janeiro.

Eduardo Paes, the Rio mayor, who was in Greece for the lighting of the Olympic torch, said in a statement that he was cutting short his visit and would return to follow the investigation into the accident.

When the structure was inaugurated, Paes hailed it as "the most beautiful bike path in the world”.

Concremat, the company which built the cycle path, released a brief statement following the accident: "The priorities at the moment are to ensure treatment of the victims and their families and evaluate the causes of the accident.”

Coming just a little more than 100 days before the Olympics, the accident a major blow to Rio’s prestige and raises questions about the engineering and safety standards of the host.

In an emailed statement, Rio’s Olympic organizers said "our thoughts and sympathies are with the people and their families and friends affected by the tragic accident”.

The ciclovia is part of the city’s efforts to improve transport links before the 2016 Games. It runs alongside the coastal expressway between two of the main Olympic centres: the south zone, which will stage the rowing and triathlon, and the main Olympic Park in Barra de Tijuca.

"I almost died,” Guilherme Miranda told the Globo newspaper. "Where’s the mayor, where’s the engineer who did this work? It’s appalling to see people dying in front of you. Someone has to give a response for that 45 million [reais]. It just opened and is already cracked in several places.”