The nation and world stood in shock when hijacked airplanes crashed into the New York skyline and the Pentagon in Arlington, Va., on Sept. 11, 2001. A fourth plane, San Francisco-bound United Airlines Flight 93, crashed in a field in Pennsylvania.
In Mountain View, city firefighters held a ceremony in honor of the 343 firefighters who died responding to the tragedy. Firefighters lowered the flag to half-mast in front of the police and fire department building.
Flag-lowering and bell-ringing ceremonies were held in cities including San Francisco, San Jose, Gilroy and Livermore.
A "healing drum circle" was planned in Oakland at the Numi Tea Garden, led by Attitudinal Healing Connection executive director Kokomon Clottey.
More than 70 drums will be available for anyone to play at the circle, which has been taking place on the Sept. 11 anniversary for the past four years, Clottey said.
At AT&T Park, red-white-and-blue banners containing the names of everyone who lost their lives 11 years ago hung outside the stadium in Willie Mays Plaza.
San Francisco Giants spokeswoman Shana Daum said the banners have gone up every year since 2002 at the plaza, with a center banner stating, "We'll Never Forget 9/11."
In Napa, a project is under way to create a memorial park on Main Street in the downtown area that will feature an art installation to honor the victims.
The park, which has yet to break ground, is expected to be completed by Sept. 11, 2013, said Jeff Gerlomes, organizer of the Napa 9/11 Memorial Coalition.
The memorial park project will eventually incorporate more than 30 tons of steel beams from the World Trade Center site.
In San Jose, a 6 p.m. flame-lighting ceremony was held at the 9/11 monument at the Oak Hill Cemetery, located at 300 Curtner Ave.
A ceremony was also held at the cemetery this morning to mark the times the twin towers were hit in Manhattan, along with the moments the planes crashed in Shanksville, Pa., and at the Pentagon.
At the Pentagon Memorial in Arlington, Va., President Barack Obama spoke, noting, "this is never an easy day."
"Eleven times we have marked another Sept. 11 come and gone," the president said. "Eleven times, we have paused in remembrance, in reflection, in unity and in purpose."
—Bay City News Service and Mountain View Voice staff