On the 12th anniversary of the 9/11 terrorist attacks, an Evanston firefighter rings a fire bell to honor fellow firefighters who died at the World Trade Center. (Credit: Bernie Tafoya)

On the 12th anniversary of the 9/11 terrorist attacks, an Evanston firefighter rings a fire bell to honor fellow firefighters who died at the World Trade Center. (Credit: Bernie Tafoya)

CHICAGO (CBS) — Fire stations throughout the Chicago area marked the 12th anniversary of the 9/11 terrorist attacks on Wednesday, with the ringing of bells, and recollections of where people were when terrorists hijacked planes and crashed them into the World Trade Center and the Pentagon.

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At the Fire Station 1 in north suburban Evanston, the mournful sound of a fire bell rang out nine times Wednesday morning – three sets of three rings indicating a firefighter has died in the line of duty.

Firefighters and police officers stood outside the firehouse to remember all those who died in the attacks in New York and Washington, D.C., and on the fourth airliner that passengers crashed into a field in Pennsylvania, to stop it from being crashed into the White House or U.S. Capitol building.

Approximately 3,000 people died in the attacks, including 23 New York police officers, 37 Port Authority police officers, 343 New York City firefighters, and 8 emergency medical technicians and paramedics from private ambulance services.

“Unfortunately, on that day, we had the greatest single loss of life in the history of the fire service on any single day, so we’re going to remember that,” Evanston Fire Chief Greg Klaiber said.

A total of 343 New York City firefighters died as they worked to rescue people from the burning Twin Towers of the World Trade Center, when the two skyscrapers collapsed.

Evanston Mayor Elizabeth Tisdahl said it’s important for those who remember 9/11 to share with young people what the day means.

“Children do not know what 9/11 was all about. They did not live through it. It is a searing part of our memories, but not of theirs,” she said. “Many of our children have no idea what 9/11 was all about, and I think about my grandchildren, and that’s true. They were too young to remember 9/11.”

While many young people don’t remember 9/11 itself, plenty were doing what they could to honor those who died.

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About 1,000 charter school students at UNO’s Veterans Memorial campus in Archer Heights, which was named after Army Spc. Daniel Zizumbo, who was killed in action while serving in Afghanistan in 2007.

The students stood outside their school and watched as flags were lowered to half-staff, and listened as a bugler played “Taps” to honor the people who died on 9/11.

Most of the children were not yet born on 9/11, but have seen the images of the aftermath of the attacks, and have heard the stories of how the nation has changed as a result.

One class at the school handed local emergency workers letters they had written to thank them for their service. It was also a way for students to honor those who died saving others twelve years ago.

“They saved us from the terrorists, and they also … risked their lives for other people that they didn’t even know,” Sebastian Orti said.

UNO CEO Juan Rangel said “We have to continue reminding everyone of the dangers of the world, especially given the circumstances around Syria today. These are great lessons for our kids to know what role we play as a nation, as well.”

One teacher told his students to spend the day reflecting on the number 343 – the number of firefighters who ran into the World Trade Center to evacuate the building, but never made it out.

Memorial ceremonies were scheduled throughout the Chicago area to mark the 12th anniversary of the 9/11 attacks; including events at firehouses in Chicago, Park Ridge, Skokie, Des Plaines, and Gary, Ind.

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A retired military officer who survived the attack on the Pentagon will speak at the Union League Club in the Loop Wenesday morning. Wednesday night in Naperville, an educator will speak about Todd Beamer, one of the passengers on United Flight 93, who took control of the cockpit from terrorists, and prevented it from being flown into the White House on 9/11.