Route changes, scuffles mark Olympic torch relaySAN FRANCISCO, California (CNN) -- Heavy security surrounded runners taking part in the controversial Olympic torch relay in San Francisco Wednesday, as the threat of violent protests prompted officials to make dramatic last-minute changes.
Plans to hold a waterfront closing ceremony were abruptly canceled.
Thousands of people who had gathered at Justin Herman Park to watch, to support China or to protest China's record on human rights and its crackdown in Tibet began leaving the site.
The announcement came during a day in which the torch's trek through the city was shortened and its path altered to try to minimize the chances that protesters would mar the event.
Anti-Chinese protesters and Beijing supporters lined the streets along the planned route hours ahead of the start of the relay.
The torch was lit in a short ceremony at AT&T Park in front of hundreds of pro-Chinese supporters who waved Chinese, American and Olympic flags.
But from the park, the runners, accompanied by Chinese security forces, went into a security warehouse and the torch disappeared from public view for about 45 minutes.
Vehicles were later seen leaving the building.
The torch was driven to a nearby neighborhood, where the runners began the relay.
There was "a disproportionate concentration of people in and around the start of the relay," Mayor Gavin Newsom told The Associated Press.
Dozens of police and security team members flanked the runners and took "very decisive" action when protesters tried to get close to the torch, CNN's Thelma Gutierrez reported.
There were several scuffles between police and demonstrators along the route. One torchbearer also got into trouble by displaying a Tibetan flag.
"The Chinese security and cops were on me like white on rice, it was no joke," Majora Carter told the AP. "They pulled me out of the race, and then San Francisco police officers pushed me back into the crowd on the side of the street."
Activists were in town from both camps: People who believe the Olympics should not be held in China and those who support the event.
The only U.S. stop for the torch relay was San Francisco, where it wrapped up the first week of a 23-city international tour.
The flame's worldwide trip from Greece to Beijing has attracted thousands of protesters, many of whom want to focus world attention on China's human rights record, its actions in Tibet and its close relationship with Sudan.
On Wednesday, British Prime Minister Gordon Brown decided he would not attend the opening ceremony in Beijing in August.
Sen. Hillary Rodham Clinton, a Democratic presidential candidate, has called on President Bush to follow Brown's lead.
The White House was vague as to whether Bush, who is slated to attend the Olympics, would attend the ceremony.
"It is way too far in advance for us to announce the president's schedule," White House press secretary Dana Perino told reporters.
Clinton also called on her rivals, Democratic presidential candidate Sen. Barack Obama of Illinois and Republican Sen. John McCain of Arizona, not to attend the ceremonies.
Obama has not announced whether he will attend the games, but has said the United States should take a stronger stance against China.
"In our policy towards China, we have not been consistent enough and tough enough in pushing them to deal with Tibet properly and also to their continued support of Sudan, a country that has been engaged in genocide against the peoples of Darfur," he said.
Obama has said he has expressed his concerns to Bush.
McCain's campaign said the president "should evaluate the situation as it evolves and ought to keep his options open."
McCain has condemned China's oppression of Tibet and has called on Beijing to open dialogue with the Dalai Lama.
On Capitol Hill, those calls for dialogue were echoed in a House resolution demanding China end its crackdown in Tibet. The passing measure was introduced by House Speaker Nancy Pelosi, who also called on Bush to consider boycotting the opening ceremony.
"When people consider whether they want to go to that opening party and give credibility and face to the Chinese government, I hope they remember that there's not a party going on among the refugees in Darfur, where people are living in subhuman conditions," she said.
For its part, China -- which blacked out domestic airing of news coverage about the crackdown in Tibet -- broadcast video showing the controversy over the Olympic flame in detail.
Beijing organizers have said the monthlong international relay will go on despite the protests, but some International Olympic Committee members have suggested considering an early end.
The International Olympic Committee's executive board will take up the topic of the torch relay "in general" Thursday or Friday, IOC spokeswoman Giselle Davies said. But there is no proposal to end the global tour early, she said.
Liu Jingmin, vice president of the Beijing organizing committee, said the Olympic torch has been "warmly welcomed by the local people" in each city.
He said the organizers "are confident that the Beijing Olympics torch relay in overseas cities will be carried out successfully."
China's Foreign Ministry has reacted more forcefully.
"We express our strong condemnation to the deliberate disruption of the Olympic torch relay by Tibetan separatist forces regardless of the Olympic spirit and the law of Britain and France," China spokeswoman Jiang Yu said Tuesday.
"Their despicable activities tarnish the lofty Olympic spirit and challenge all the people loving the Olympic Games around the world."
Beijing blames the Dalai Lama and his followers for violence that erupted in March amid protests for Tibetan independence.
China has drawn international criticism for its crackdown on the demonstrations, which began peacefully on the 49th anniversary of a failed Tibetan uprising.