Although 25 years have passed, the horrific events of Sept. 11, 2001 will forever be seared into the memories of those who witnessed the worst terrorist attack in American history.

David Glaser, now a sergeant with the Hudson Police Department, was in Stamford, Conn. when American Airlines Flight 11 slammed into the North Tower of New York City’s World Trade Center.

“As soon as Tower One was hit, I immediately called my sister to see if my brother-in-law, Port Authority Police Officer David Lim, was working — he was,” said Glaser. “David had pinned my badge when I graduated from the academy and we are very close.”

That morning, Glaser was faced with a dilemma. He wanted to keep his sister, Diane, calm, however, he also had a strong urge to drive to Manhattan to make sure Lim was okay and help with the evacuation effort. He ultimately elected to stay on the phone with his sister.

“Diane told me that David was working in Tower One with his K9 partner, Sirius,” said Glaser. “I assured Diane that Dave’s training would kick in and he would be safe.”

At 9:03 a.m., Diane abruptly hung up with Glaser and called Lim as the South Tower had just been hit by United Airlines Flight 175. She called Glaser back and said that Lim was okay and was on the 27th floor of the North Tower.

When the South Tower collapsed at 9:59 a.m., Diane called her husband again. He said he was on the 44th floor of the North Tower and that all first responders had been ordered to evacuate.

When Lim made it to the fifth floor, he heard a rumbling sound, the same sound he heard when the South Tower came down a half hour earlier. It was the North Tower coming down.

“When the dust settled, he found that he, 12 firefighters and three civilians were in what was essentially a cave within Stairwell B,” said Glaser.

Unlike the South Tower, the exterior columns of the North Tower fell outward creating a protective cocoon at the bottom of the building. By the time the collapse reached the lower floors, the kinetic energy had diminished and became survivable.

“Dave was able to make a cell phone call from under the rubble to my sister in Long Island and pinpoint where they were,” said Glaser. “They were there for approximately six hours before rescue and miraculously, all made it out alive.”

All except Sirius, who was left in his kennel and died in the collapse.

“As a native New Yorker, I felt defeated,” said Glaser. “From Tod’s Point in Greenwich, Conn., I could look across the water and see the empty space where the towers used to stand, only smoke and dust billowing into the sky.”

That night, all Glaser could hear were fighter jets patrolling the skies.

“I felt sorrow, anger, pride and despair,” he said. “The strongest emotion seemed to change by the minute.”

Twenty-five years later, Glaser said his sense of pride has changed the most.

“What has changed is the pride I felt in how the country responded afterward, all anyone cared about was finding survivors, helping the survivors of those who lost loved ones and finding those responsible to hold them accountable,” he said. “Race, religion or political affiliation didn’t matter. The country was more united than I have ever seen it. Today, it is more divided than I have ever seen it. Twenty-five years later, I wish we could remember not only what happened to us that day, but who we became in the days that followed.”

Londonderry Police Capt. Patrick Cheetham had just started his junior year at St. Anselm College. On the morning of 9/11, he was scheduled to be sworn in as a patrol officer with the Litchfield Police Department.

“I was a young 20-year-old excited to become a police officer,” he said.

After the order was given to close U.S. airspace, Cheetham, while driving up Brown Avenue in Manchester, watched plane after plane land at Manchester-Boston Regional Airport.

“Homeland security became everyone’s mission,” he said.

Despite the Never Forget mantra, Cheetham said 25 years has taken its toll on how Americans remember that Tuesday morning in September 2001.

“I do think there’s a softening of the reality,” he said. “We’re hiring police officers that were born after 9/11.”

Nashua Ward 3 Alderwoman Patricia Klee worked for the U.S. Department of Veterans Affairs in Bedford, Mass. and was assisting a co-worker with an Excel spreadsheet.

“From the hallway, we heard someone yell that a plane had crashed into one of the Twin Towers,” she said. “Then we heard another plane hit a tower, we scrambled to get news to understand what was happening.”

Klee and her colleagues turned on the television and watched as the 110-story South Tower fell to the ground.

“As a department of the federal government, we went on high alert and semi-lock down,” said Klee. “The outside world was in chaos, but we needed to remain calm and check on our staff and our veteran patients.”

Klee’s husband also worked for the VA in an adjacent building.

“As all of the office phones were put on emergency use only and cell phone service became difficult,” she said. “I ran across the parking lot to his office to make sure he was safe and to get a hug. We all wanted to call our families just to check in and hear their voices.”

Klee also said many of her colleagues were travelling abroad at the time of the attacks.

“There were many briefings and plans to move forward to get our people home,” she said.

Twenty-five years later, Klee said 9/11 is still an “open wound.”

“I know that I will never forget that day or the moment that I heard, ‘a plane just hit one of the Twin Towers’ or the moment we saw the first tower collapse on the news,” she said. “We all cried and held hands or hugged for comfort.”

Ward 5 Alderwoman Paula Johnson was serving on the Board of Education at the time of the attacks.

That morning, she had taken her car in for repairs when she saw the events unfold on television. Originally from New York, Johnson was in disbelief. Pilots were always directed to go around the towers. However, on that day, terrorists were in the cockpit.

“I watched it on television, seeing the World Trade Center, in my hometown, being destroyed,” she said.

Ward 8 Alderman Derek Thibeault was working for Oxford Health Plans in the fall of 2001. His company’s largest membership was in New York City.

“We had customers on the phone reacting to what was happening,” he said. “We had companies in the towers and customers who died. We shut down as quickly as we could and I went home glued to the television.”

Although numerous safety improvements have been made, Thibeault said the possibility of another attack is always in the back of his mind.

Board of Education member Robert Johnson was living in New York City and remembered people complaining because the N train was running late.

“The announcement was a ‘police action’ but we all thought it was another lame excuse for late trains,” he said.

Johnson came up out of the subway and onto 59th Street. Standing in front of the General Motors Building, he looked down Fifth Avenue and saw billowing smoke in the distance.

“People talked about something striking one of the towers,” he said. “Then, a second hit, clearly a jet liner? Too big to be a small plane. I stood and watched with several others, now all late for work.”

Johnson also remembered getting a page from his father and calling back on a Park Avenue pay phone.

“I saw the first tower fall as my dad watched on television on the other end,” said Johson. “Seeing was so hard to believe.”