A brave cyclist was tragically killed by a disturbed individual at a train station in San Francisco after he intervened to defend a mother and her children who were being threatened.

Colden Kimber, aged 28, lost his life when he was stabbed in the neck with a six-inch knife on July 26 while waiting with his girlfriend at a Muni site in the Ingleside neighborhood.

Earlier, the couple had been on a date and arrived at the station around 4:15 pm, amidst a gathering of families and children, when 29-year-old Sean Collins approached them.

As they were waiting, Kimber courageously positioned himself between Collins and the woman with her children, whom Collins was confronting with taunts such as ‘Oh, you think you’re better than me’ and ‘You’re scared of me,’ according to court documents referenced by KGO reported.

Standing at 6’4″, Kimber positioned himself right in front of Collins as the train was arriving, at which point the attacker unexpectedly stabbed him on the right side of his neck, according to records.

Following the ‘completely and utterly unprovoked’ attack, Kimber stopped moving as blood gushed out of his neck, the court filing read. 

He was rushed to San Francisco General Hospital where he died after undergoing surgery. 

Shortly after the deadly incident, Collins was found covered in blood by police blocks away from the scene and taken into custody. 

Surveillance footage from a nearby restaurant also captured Collins walking in the area dressed in an all black outfit. 

Collins has been charged with murder and is due in court for his arraignment on August 14. 

It is unclear what drove him to stab Kimber, but according to court documents, the Superior Court of California received a report regarding his mental health. The results of the report remain unclear at this time. 

Cameras at the Muni station captured the attack and two child witnesses, aged eight and 14, saw the horror stabbing occur, according to prosecutors. 

Now, Kimber’s loved ones are trying to make sense of the crime that took the life of someone who was trying to save others. 

Bradley Woehl, the owner of American Cyclery, where Kimber worked, said he is a ‘totally irreplaceable’ employee who he will miss dearly. 

‘I’m going to miss him for his good nature and his kind spirit, and he really lived such an exemplary life. He was a very positive influence on myself and my staff,’ Woehl told KGO.

He added that Kimber worked at the shop for years, where he would repair and even build new bikes for customers. 

‘He is totally irreplaceable as a worker, and totally irreplaceable as a friend and person and someone who had a good influence in my life,’ his boss added. 

Kimber discovered his passion for cycling when he took his mother’s place in the New York triathlon after she had to drop out while fighting breast cancer, she told the San Francisco Chronicle. 

‘He had never ridden a bike on a road,’ Lara Litchfield-Kimber said. ‘The bikes were the things that stuck.’ 

After relocating from New York to California in 2020 with his long-time girlfriend, Kimber joined the Dolce Vita Cycling team as well as a semiprofessional ice hockey team in Vacaville.

He previously played hockey growing up, his mother explained. 

Kimber loved biking so much he would be on his bike for 12,000-13,000 miles some years, per the Chronicle. 

When he wasn’t dabbling in sports, Kimber was studying kinesiology at San Francisco State University. He dreamed of working in sports medicine. 

Litchfield-Kimber set up a GoFundMe page to help support their family during this difficult time. 

‘Colden unwillingly leaves behind a loving partner of seven years, his little sister who is just getting into road cycling, friends young and old, beloved cycling and hockey communities on both sides of the country, and his family who was immensely proud of the man he had become,’ she wrote. 

In addition to trying to plan services and memorials for her late son, his grieving mother said his family plans to ‘simultaneously navigate a criminal homicide trial from across the country and all the unknowns of this unfamiliar process.’ 

As of Sunday afternoon more than $81,500 was raised to help them out.

Daily Mail contacted the San Francisco District Attorney’s Office for comment.