Jon Meis tackled Aaron Ybarra, 26, who opened fire on Thursday at Seattle Pacific University, killing one person and wounding several others.
The rampage only stopped when Jon was brave enough to grab him, pepper spraying him and confining him until the police could arrive.
Investigators into the incident called Meis a hero, saying they were in awe of his absolute selflessness when faced with the gunman, who was intent on killing as many people as possible.
Even more incredible is that Jon was just two weeks away from his wedding, making his act of valour all the more amazing.
As local people began to learn of the heroic acts of Jon, they started buying the gifts listed on the couple's wedding registry.
Random strangers even shared the link to Meis' registry so that others could help out if they chose to.
One Twitter user wrote: 'Here is the wedding registry of the guy who stopped the SPU shooter yesterday. You know what to do.'
By Friday, just one day after the shooting, people had purchased every single item on the couple's wish list - which included simple things like strainers, a grater, and tongs.
But feeling that this wasn't quite enough to show the people of Seattle's gratitude, Jessamyn McIntyre started a crowd funding campaign to send the young couple on a dream honeymoon.
In three days, almost 2,000 people donated to raise $50,395 for the couple's 'honeymoon and future.'
Jon then asked that donations on the page be turned off, and that any further money people wished to donate go to the victims of the shooting.
'Words cannot come close to expressing he tragedy that occurred this past week on our campus,' he wrote.
'While my experience left me in physical shock, I know that many people are dealing with much greater grief than I have ever experienced, and in honesty I probably would not be able to handle it myself right now if I had personally known the victims.'
'In the midst of this attention, we cannot ignore that a life was taken from us, ruthlessly and without justification or cause. Others were badly injured, and many more will carry this event with them the rest of their lives.'
A 19-year-old first year student was killed in the shootings, and three others wounded - numbers that no doubt would have been far larger if Jon had not acted when he did.
Ybarra told detectives that he wanted to kill as many people as he could.