A veteran commander of the Alameda County Sheriff’s Office who oversees Santa Rita Jail has more votes than her boss, but the two appear headed to a November runoff election, based on the initial results in Tuesday’s election.

Sheriff’s Cmdr. Yesenia Sanchez had nearly 47 percent of the overall count, compared to 36 percent for current Sheriff Greg Ahern, who became sheriff in 2006 and is seeking a fifth term in office. San Francisco Police Officer Joann Walker finished in third place with roughly 17 percent of the vote, according to the unofficial results Tuesday night.

If no candidate reaches more than 50 percent of the vote, the top two candidates — in this case, Sanchez and Ahern — would then face off in a November runoff.

A runoff also appears likely in the races for the county’s district attorney and the District 3 seat on its Board of Supervisors.

Civil rights attorney Pamela Price was in the lead with nearly 40 percent of the vote to replace the retiring District Attorney Nancy O’Malley, according to the unofficial results Tuesday night, with Chief Assistant District Attorney Terry Wiley appearing to reach a runoff with Price by having the second-most votes and more than 31 percent of the overall turnout in the race.

Another member of O’Malley’s staff, Deputy District Attorney Jimmie Wilson, finished third while fourth place was Seth Steward, who serves as chief of staff for Oakland City Councilmember Dan Kalb.

In the race to be the new District 3 supervisor, a seat that is empty after former Supervisor Wilma Chan was struck and killed by a driver as she walked in Alameda late last year, Oakland Vice Mayor Rebecca Kaplan had the most votes at nearly 39 percent, while former Alameda Vice Mayor Lena Tam had about 30 percent of the vote, according to the unofficial results.

If those results hold, Kaplan and Tam would head to a November runoff. David Kakishiba, executive director of the East Bay Asian Youth Center, and Surlene Grant, a former vice mayor of San Leandro, appeared to finish third and fourth, respectively.

Chan’s former chief of staff David Brown was appointed to fill the seat following her death and until Tuesday’s election could be held.