Every one of of San Francisco's 44 fire stations held a somber ceremony this morning, marking the 16 years since an attack on the World Trade Center killed nearly 3000 people.

The Chron reports that at 6:45 a.m. Monday, "the bay doors of fire stations across the city rose and fire engines and other apparatus rolled into the driveways as firefighters lined up formation in front of flag poles and saluted as as American flags were raised."

Just after sunrise, at 6:59 a.m. (which is when the South Tower of the World Trade Center collapsed on September 11 of 2001), every fire station rang their bells to mark "the last alarm 343 New York City firefighters answered on the day they rushed into the twin towers and were killed while saving lives."

At 7 a.m., every fire department flag was lowered to half staff. Following a moment of silence, the names of the fallen firefighters were read.

In a statement sent early Monday, Mayor Ed Lee honored the first responders killed that day, writing that on the day of the attacks, "we witnessed incredible acts of courage and heroism from our nation's first responders. Faced with unimaginable danger, thousands of police officers and fire department officials risked their lives to save others."

"The anniversary of 9/11 is a time to reflect on what we lost, and celebrate the brave people who serve our communities," Lee wrote. "Today, we salute the thousands of individuals who work selflessly on the behalf of San Franciscans. Thank you for your service."