SAN FRANCISCO — Hundreds of protesters took to the streets Thursday over California's new ban on gay marriage, amid deepening political turmoil and legal confusion over who should have the right to wed.

And hundreds more may converge on The Church of Jesus Christ of Latter-day Saints' Temple Square in downtown Salt Lake City tonight, according to event organizer Jacob Whipple.

Whipple said in a press release Thursday that protesters are invited to gather for a rally on State Street and North Temple at 6 p.m. They will march around the two downtown blocks of Temple Square and the Church Office Building to show "solidarity with the protests and marches that have occurred in Los Angeles and San Francisco," the release said.

Legal experts said it is unclear whether an attempt by gay-rights activists to overturn the California prohibition has any chance of success, and whether the 18,000 same-sex marriages performed in the state over the past four months are in any danger.

California voters Tuesday approved a constitutional amendment disallowing gay marriage. The measure, which won 52 percent approval, overrides a California Supreme Court ruling last May that briefly gave same-sex couples the right to wed.

On Thursday, about 1,000 gay-marriage supporters demonstrated outside an LDS temple in the Westwood section of Los Angeles. Sign-waving demonstrators spilled onto Santa Monica Boulevard, bringing afternoon traffic to a halt. The temple was targeted because the LDS Church strongly supported the ban on gay marriage.

"I'm disappointed in the Californians who voted for this," said F. Damion Barela, 43, a Studio City resident who married his husband nearly five months ago. He noted that nearly 70 percent of black voters and a slight majority of Hispanic voters voted for the ban.

"To them I say, 'Shame on you because you should know what this feels like,"' he said.

Some spectators cheered from apartment balconies; one person threw eggs at the marchers. Two people were arrested after a confrontation between the crowd and an occupant of a pickup truck that showed a banner supporting the amendment.

On Wednesday night, police in Los Angeles arrested seven people as more than 1,000 protesters blocked traffic in West Hollywood. One man was wrestled to the ground by police after he jumped up and down on the roof of a squad car. Another man was clubbed by police. Hundreds of protesters also gathered on the steps of San Francisco's City Hall, some holding candles and carrying signs that read, "We all deserve the freedom to marry."

Gay-marriage proponents filed three court challenges Wednesday against the new ban. The lawsuits raise a rare legal argument: that the ballot measure was actually a dramatic revision of the California Constitution rather than a simple amendment. A constitutional revision must first pass the Legislature before going to the voters.

"Where do you draw the line between 'revision' and 'an amendment' when those are words in conversation we would use interchangeably?" asked Erwin Chemerinsky, dean of the University of California, Irvine law school. "It's a highly technical legal question in a highly charged political atmosphere."

Andrew Pugno, attorney for the coalition of religious and social conservative groups that sponsored the amendment, called the lawsuits "frivolous and regrettable."

"It is time that the opponents of traditional marriage respect the voters' decision," he said.

The high court has not said when it will act. State officials said the ban on gay marriage took effect the morning after the election.

"We don't consider it a 'Hail Mary' at all," said Kate Kendell, a Utah native and executive director of the National Center for Lesbian Rights. "You simply can't so something like this — take away a fundamental right at the ballot."

With many gay newlyweds worried about what the amendment does to their vows, California Attorney General Jerry Brown said he believes those marriages are still valid. But he is also preparing to defend that position in court.

"I wish I could be comforted by Attorney General Brown's statement that it has no retroactivity," said Loyola Law School professor Bill Araiza, who married his same-sex partner Oct. 29. "But it's in flux and I just don't know."

The amendment does not explicitly say whether it applies to those already married. Legal experts said unless there is explicit language, laws are not normally applied retroactively.

"Otherwise a Pandora's Box of chaos is opened," said Stanford University law school professor Jane Schacter. Still, Schacter cautioned that the question of retroactivity "is not a slam dunk."

An employer, for instance, could deny medical benefits to an employee's same-sex spouse. The worker could then sue the employer, giving rise to a case that could determine the validity of the 18,000 marriages.

Supporters of the ban said they will not seek to invalidate the marriages already performed and will leave any legal challenges to others.

A 2003 California law already gives gays registered as domestic partners nearly all the state rights and responsibilities of married couples when it comes to such things as taxes, estate planning and medical decisions. That law is still in effect.