Confusion and delays surrounded the relay of the troubled Olympic torch through San Francisco tonight, as thousands of China supporters and protesters converged along the planned route.
The first runner held the torch aloft and began the route, flanked by tall, blue-clad Chinese security officials.
But the group then promptly disappeared into a large waterfront warehouse complex - in what appeared to be a possible last-minute change of route by authorities to head off trouble.
The torch was a magnet for chaotic demonstrations in London and Paris in the last week over a range of China issues from China's crackdown on Tibet last month to human rights.
The protests have angered Beijing as it starts to count down to host the Olympic Games in August.
In San Francisco, a city with a large Chinese-American population many of whom were proudly waiting to see the torch relay, there were tense confrontations.
At least one pro-Tibetan demonstrator was detained even before the starting event, which began later than the scheduled 1 p.m. (2000 GMT).
Despite the protests in Europe and the threat of more protests in San Francisco, Olympics chief Jacques Rogge said there were no plans to cut short a global relay ahead of the Olympic Games opening.
Hundreds of security officers, including agents from the FBI, backed by police cars with flashing lights, harbor boats, jet skis and helicopters have been deployed.
Police warned anyone crossing barricades would be subject to arrest; officials shortened the route at the last minute and decided that two torch bearers should run concurrently.
Reflecting divided feelings in the city - a fifth of whose population is of Chinese origin - thousands of pro-China spectators gathered along the route, many flying the five-star Communist Chinese flag alongside US and Olympic flags.