The accident on the Tim Maia bike path is the latest in a series of problems besetting preparations for the Aug. 5-21 games. Municipal Secretary Pedro Paulo Carvalho said a third person was thought to be missing after a giant wave apparently swept up a rocky cliff. Tho other people were rescued alive. It was too early to tell if construction might be to blame for the accident. An investigation is under way to determine the cause of the collapse. The entire 4-kilometer- (2.5-mile) bike path, which links the beachfront neighborhoods of Sao Conrado and Leblon, is now closed. Rio’s Olympic organizers said “our thoughts and sympathies are with the people and their families and friends affected by the tragic accident,” in an e-mail statement.