Cambridge City Councilor Sam Seidel was the only incumbent councilor to lose his seat in the municipal election Tuesday.
Challenger Minka vanBeuzekom will replace Seidel on the council after winning a race that included 18 candidates for the 9-seat board.
School Committee incumbent Nancy Tauber was also defeated in the election Tuesday and will be replaced by Mervan Osborne on the committee, according to unofficial results posted by the Cambridge Election Commission at 11:45 p.m. Tuesday.
Seidel had served two terms on the council before his defeat Tuesday, and Tauber had been a member of the School Committee since she was elected in 2007.
City Council incumbents who were re-elected Tuesday were: Leland Cheung, Henrietta Davis, Marjorie Decker, Craig Kelley, David Maher, Kenneth Reeves, E. Denise Simmons and Timothy Toomey Jr..
Returning to the School Committee will be newly re-elected incumbents Alfred Fantini, Richard Harding Jr., Marc McGovern, Patricia Nolan, and Alice Turkel.