SOMERVILLE--Dorothy Kelly Gay was elected the first female mayor of Somerville yesterday, defeating alderman John Buonomo in a special election to fill the post formerly held by Michael A. Capuano.

At a jubilant victory party last night, Gay credited her victory in large part to her support from female voters and pledged to bring a new perspective to city hall.

Gay and Buonomo have been campaigning since Capuano, now a congressperson, left the mayoral position open in January. Gay will hold the position until the regular mayoral election in November.

According to the Somerville election commission, the final vote tally was 6878 votes for Gay and 6473 for Buonomo.

The close margin kept the candidates' spirited supporters on edge at victory parties last night.

Gay was very happy with her victory, saying she felt "excited and overwhelmed."

She spoke proudly of being the city's first female mayor.

"We've charted new waters. We've charted a new course. The women of Somerville came out in force," she said.

Former Somerville Mayor Gene C. Brune said Gay's hard work had paid off.

"I feel great. It's a well-deserved win. She was the underdog up until about three weeks ago, but you could feel the momentum building," he said.

Brune credited female voters for a great deal of this momentum.

"I think it's the women who gave her the victory," he said.

Teresa Cardoso, a school committee member for Somerville's ward two said she counted herself among these female supporters.

"It will be great to have a qualified female mayor for the first time in the city's history, " she said.

Venture capitalist and former Eighth District congressional candidate John O'Connor said Gay's status as a political outsider allowed her a fresh perspective.

"She's never been part of the good old boys' network. I think you'll see much more effective experimentation on many issues," O'Connor said.

Despite her supporters' confidence, Gay's victory was far from assured at the beginning of the evening.

Before results rolled in, Buonomo's supporters, who gathered at the Holiday Inn on Washington Street, were certain that the long-time city official would come out ahead.

One of these confident supporters was Buonomo's aunt, Rose M. Earle.

"He's been at this for more than 18 years. My nephew knows every nook and cranny of this city...he knows how to look forward. Tonight is going to be a big victory," Earle said.

Therese E. Stile, a lifelong Somerville resident, also said that Buonomo's experience would help him win.

"I've known John for many years. He grew up with my children," Stile said. "It was his time to run for mayor. He's the most qualified to do so, in my estimation."

But as results for the first two reporting precincts came in, an audible sigh arose from the several hundred people attending Buonomo's planned victory celebration. Gay had won ward two, precinct one by 39 votes and ward two, precinct two by 35.

The mood lifted and audience members cheered when they heard their candidate had won the second precinct of ward one by 56 votes, but this was among the last bursts of optimism.

At about 9 p.m., Buonomo conceded defeat. He thanked his supporters and the city as a whole.

"In the last seven months I have met some very beautiful people, some very caring people," he said.

"I have always believed that you must be ready to both win and to lose," he added.

But his supporters aren't giving up yet.

There was immediate speculation that Buonomo would run against Gay again this fall in the regular mayoral elections.

George S. Huges was one hopeful supporter.

"I get this gut feeling that he'll run again in September," he said.

But Buonomo was non-committal.

"I'm honored by the thought, but I have no idea what I'm going to do," he said.

Meanwhile, another former challenger of Gay says he will not run against her again.

Joe Curtatone, the third-place candidate in March's primary, affirmed his support for Gay.

"I am not a candidate for mayor. I'm here working with [Gay]. This is a victory for all of us. All of my people came here tonight and have worked hard [for Gay], " he said.