SOMERVILLE--Dorothy Kelly Gay was elected the first female mayor of Somerville yesterday, defeating council member 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 state representative, 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 6,878 votes for Gay and 6,473 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.