Despite heavy rains, hundreds of gay and lesbian couples poured into the San Francisco City Hall to get married on Monday, before court hearings on attempts to block same-sex unions.

Newly elected San Francisco Mayor Gavin Newsom last Thursday opened City Hall to gay couples wanting to marry and decreed that the building would remain open throughout the three-day Valentine's-Presidents Day weekend.

More than 1,700 marriage licences have been issued since then and hundreds, many from as far as New York and Florida, have already been married.

The demand was so high that on Sunday, City Hall was closed before noon and hundreds of people were turned away because officials said they didn't have the time or resources to meet all the requests.

"We're already a family," Mara McWilliams, a 34-year-old health worker from San Jose told the Los Angeles Times, as she waited in line for her turn in the clerk's office on Sunday morning.

Her eight-year-old daughter, Serena, clutched her leg as McWilliams' partner of four years, Renee Mangrum, dashed off to get coffee. "This is to show the world we're already a family. We're normal, professional people. We're not here with our freak on."

However, the unprecedented move has also set off legal challenges forcing state courts to determine whether barring same-sex couples from marrying is discriminatory and unconstitutional.

The Arizona-based Alliance Defence Fund sued to block the same-sex unions and a second legal challenge was filed by a California group.

The Campaign for California Families sued the San Francisco mayor "for violating California state law on marriage and the issuing of marriage licences".

Newsom, who took office on January 8, said gays and lesbians should be able to marry based on the California constitution's guarantee of equal protection under the law.

"I'm not interested as a mayor in moving forward with a separate but unequal process for people to engage in marriages," Newsom said in an interview Friday on ABC News' Good Morning America.

"I think the people of this city and certainly around the state are feeling that separate but unequal doesn't make sense."

Governor Arnold Schwarzenegger and other state officials have avoided comment, but Attorney General Bill Lockyer's spokeswoman noted that California's constitution provides broader equal protection rights than other states.