Today marks the 17th anniversary of the terror attack on New York - which saw almost 3,000 people lose their lives and changed the landscape of the city forever.
Shortly after the Twin Towers of the World Trade Center collapsed - after being hit by two separate planes - almost 10,000 emergency rescue workers joined forces to help the search and rescue effort.
Amid a sea of noise, chaos, confusion and dust, their job began - an unimaginable task that no number of hours training could ever prepare them for.
Of those brave heroes - who ran towards danger when everyone else was running away, scared for their lives - around 300 were dogs.
Along with remembering those lost and the amazing men and women who risked their lives to help, we must remember and honour the Hero Dogs of 9/11.
Countless number of people owe their lives to the tireless help of the animals, who played a major part in the recovery directly after the attack on the towers.
From search and rescue dogs to comfort dogs to bomb detection dogs, these canines' stories of courage, healing and long-lasting legacy must never be forgotten.
The last living hero dog from 9/11 was Bretagne (pronounced Brit-nee). Sadly, she passed away in 2016, at the grand age of 16.
At the time of the attacks she was a two-year-old bouncing golden retriever working day-to-day with her owner and handler, Denise Corliss.
When the towers fell Bretagne and Denise spent ten day at the site going from rescue to recovery.
Denise, a volunteer firefighter with the Cy-Fair Fire Department, began training Bretagne for search and rescue work at just eight weeks old.
Bretagne retired from formal search work at nine, but continued to work as a goodwill ambassador for her local fire department, and as a reading assistance dog at a local schools.
When she passed away, she entered the animal hospital in Cypress, Texas, where firefighters and search and rescue workers from the fire department lined the sidewalk and saluted.
She was carried out later, her body draped in an American flag.
Apollo, the German Shepherd and his handler Peter Davis were called in to assist with rescue operations after the 9/11 terror attacks.
They were the first search and rescue dog team to arrive on the scene - just 15 minutes after the collapse of the towers.
Apollo nearly lost his life on the day as he narrowly missed being engulfed by flames and crushed by falling debris.
Thankfully he survived, only because he was drenched after falling into a pool of water just beforehand.
Another German Shepherd, Trakr, along with the Canadian Police officer James Symington, discovered the last survivor of the September 11 attacks at the World Trade Center.
Genelle Guzman-McMillan was making her way down the stairs in the South Tower when the building collapsed around her.
Trakr was able to locate her after she'd been trapped under the rubble for 27 hours, and alerted firefighters.
Because Trakr was such an amazing hero, his DNA was entered into a cloning contest by Symington and was later chosen for use after his death, in April 2009
The following June, five cloned Trakrs were born.
This last hero hound wasn't a search and rescue dog. Labrador Roselle was a seeing-eye dog working with her companion, Michael Hingson, in the North Tower.
When the plane hit Michael was aided to safety by Roselle down, almost 80 floors.
Roselle fought through scattered rubble, debris and a giant dust cloud to help not only her master, but 30 other people, get to safety.
One hero wasn't so lucky though. Sirius, an explosive detection dog with the Port Authority of New York and New Jersey Police Department, was the only police dog to die in the 9/11 attack as he was in his kennel at the bottom of the World Trade Center when it collapsed.
These are just a small handful of heroes who entered the chaos with no concern for their own lives.
They went in, came out, got their paws and noses cleaned, and went back in again - often working for up to 12 hours at a time.
At the time, is was reported that some of the dogs were starting suffer from depression because they weren't finding survivors, just bodies.
Specialist vets and their handlers had to work with them to keep their spirits up and remind them that the job they were doing was no less amazing than anyone else.
Sadly, none of the hero dogs of 9/11 are with us any more, but because of their courageous efforts many people were saved, and their legacy will live on forever.
Featured Image Credit: Barcroft Media